There seem to be more meadow voles on our Littleton farm this year. Perhaps this is due to a better food crop following the copious rain and snow this spring; more likely, it reflects the eviction of our fox family, primary predators of these prolific rodents. Then, again, we have plenty of hawks, kestrels and owls around to keep their numbers in check.
Meadow voles spend most of their brief life in burrows and runways beneath dense grass (or beneath snow in the winter); several of their entry portals are evident along our driveway, which borders one of the pastures. Females are able to breed by one month of age and, in their 12-18 month lifespan, produce a litter of 4-12 youngsters every 3-4 weeks; to some degree, birth rates rise and fall relative to the local food supply. Obviously, meadow voles are one of the most prolific mammals on the planet.
When not breeding, these voles are eating, consuming over 50% of their body weight each day. Active day and night, they feed primarily on grasses, herbs and weeds during the warmer months, converting to seeds, sapling bark, berries and dead vegetation in winter. Though almost exclusively herbivorous, they are known to eat insects and occasionally cannibalize the young of other voles; at least they're taking some responsibility for population control!
Friday, September 19, 2008
The Scratchers
Many birds attract our attention with their colorful plumage; certain buntings, grosbeaks, tanagers, orioles and waders come to mind. Others have distinctive calls; even novice birders can identify magpies, crows, blue jays, flickers and belted kingfishers without actually seeing them.
Then there are the scratchers. While most ground-feeding birds sift through leaf litter for seeds or insects, some species are especially vigorous in this regard; robins, thrashers, hermit thrushes and fox sparrows are excellent examples. But the king scratchers are the towhees and their energetic feeding style often calls our attention to their presence.
Of the four species in North America, the rufous-sided towhee is the most common and widespread; this species, which has eastern and western races, is a permanent resident in much of the U.S., though it departs more northern regions in winter. Here in Colorado, it is joined by the green-tailed towhee, which inhabits foothill shrublands and canyons during the warmer months. The other two species, Abert's and brown towhees, are restricted to desert and semiarid regions of the Southwest.
Then there are the scratchers. While most ground-feeding birds sift through leaf litter for seeds or insects, some species are especially vigorous in this regard; robins, thrashers, hermit thrushes and fox sparrows are excellent examples. But the king scratchers are the towhees and their energetic feeding style often calls our attention to their presence.
Of the four species in North America, the rufous-sided towhee is the most common and widespread; this species, which has eastern and western races, is a permanent resident in much of the U.S., though it departs more northern regions in winter. Here in Colorado, it is joined by the green-tailed towhee, which inhabits foothill shrublands and canyons during the warmer months. The other two species, Abert's and brown towhees, are restricted to desert and semiarid regions of the Southwest.
Thursday, September 18, 2008
Cottonwood Cathedrals
On my frequent walks along the South Platte River, I often stop to enjoy the shady, peaceful environment of the cottonwood groves. Common along the rivers and creeks of eastern Colorado, between elevations of 3500 and 6000 feet, the plains cottonwood matures into a massive tree with a thick trunk and a wide, branching crown. Older groves are cathedral-like in their natural splendor and provide home to a wide variety of creatures.
Magpies and hawks construct bulky nests in their upper branches, often used by great horned owls in later years. Fox squirrels, raccoons, opossums, screech owls, wood ducks and bats use cavities in these majestic trees and their spreading crown attracts riparian songbirds; among the latter are western wood pewees, yellow warblers, chickadees, white-breasted nuthatches, downy woodpeckers and northern orioles. Northern flickers often dominate these groves and dead trees are favored nest or roosting sites for bald eagles, ospreys, double-crested cormorants, great blue herons, black-crowned night herons and belted kingfishers. An understory of wild plum, wax current, wild rose and sand willow diversifies the resident wildlife, attracting house wrens, brown thrashers, gray catbirds, blue jays, white-footed mice, long-tailed weasels, six-lined racerunners and a variety of snakes.
Of course, these cottonwood groves are especially "productive" for birders during the spring and fall, when migrant songbirds hunt along the streams as they move to and from the mountains. In like manner, new residents, including northern cardinals and white-throated sparrows, have moved into Colorado via these riparian woodlands. Long threatened by agriculture, timber production and flood control, these natural cathedrals are a source of inspiration and reflection; amidst their majestic beauty, we are reminded that our natural heritage remains under assault.
Magpies and hawks construct bulky nests in their upper branches, often used by great horned owls in later years. Fox squirrels, raccoons, opossums, screech owls, wood ducks and bats use cavities in these majestic trees and their spreading crown attracts riparian songbirds; among the latter are western wood pewees, yellow warblers, chickadees, white-breasted nuthatches, downy woodpeckers and northern orioles. Northern flickers often dominate these groves and dead trees are favored nest or roosting sites for bald eagles, ospreys, double-crested cormorants, great blue herons, black-crowned night herons and belted kingfishers. An understory of wild plum, wax current, wild rose and sand willow diversifies the resident wildlife, attracting house wrens, brown thrashers, gray catbirds, blue jays, white-footed mice, long-tailed weasels, six-lined racerunners and a variety of snakes.
Of course, these cottonwood groves are especially "productive" for birders during the spring and fall, when migrant songbirds hunt along the streams as they move to and from the mountains. In like manner, new residents, including northern cardinals and white-throated sparrows, have moved into Colorado via these riparian woodlands. Long threatened by agriculture, timber production and flood control, these natural cathedrals are a source of inspiration and reflection; amidst their majestic beauty, we are reminded that our natural heritage remains under assault.
Wednesday, September 17, 2008
A Hornet Nest
Since my last visit to our Colorado farm, a gray, basketball-sized, turban-shaped globe has appeared in one of our apple trees; not to be mistaken for a pinata, this is, of course, a hornet nest. No doubt present during my visit in July, the nest has "grown" to a more conspicuous size over the past two months.
Pregnant female hornets emerge from their winter retreat in spring and lay eggs in a cluster of paper cells that they attach to a tree limb; unlike other wasps, they enclose these cells in a protective envelope (the "paper" is formed by salivary digestion of wood scraps). Once the eggs hatch, the attentive queen feeds them until the larvae pupate; emerging as sterile female workers, this initial brood returns the favor by expanding the hive and tending to the queen, who will continue to lay fertilized eggs throughout the spring and summer. Space for the new egg chambers is made by scraping away the inner layer of the envelope and adding a new layer to the outside; over the months, the enlarging envelope houses a growing colony of worker hornets, larvae, pupae and eggs. Access to the nesting cells is via an opening on the underside of the globe; watching from a safe distance, one can see worker hornets arriving and departing throughout the day as they gather nectar and paper substrate.
As the autumn chill arrives, the queen lays eggs that will hatch into fertile males and females; these non-workers will mate and the pregnant females will become next year's queens. Once the winter freeze sets in, the hive is abandoned, the future queens retreat to warm dens (either underground or in structures) and all others perish.
Pregnant female hornets emerge from their winter retreat in spring and lay eggs in a cluster of paper cells that they attach to a tree limb; unlike other wasps, they enclose these cells in a protective envelope (the "paper" is formed by salivary digestion of wood scraps). Once the eggs hatch, the attentive queen feeds them until the larvae pupate; emerging as sterile female workers, this initial brood returns the favor by expanding the hive and tending to the queen, who will continue to lay fertilized eggs throughout the spring and summer. Space for the new egg chambers is made by scraping away the inner layer of the envelope and adding a new layer to the outside; over the months, the enlarging envelope houses a growing colony of worker hornets, larvae, pupae and eggs. Access to the nesting cells is via an opening on the underside of the globe; watching from a safe distance, one can see worker hornets arriving and departing throughout the day as they gather nectar and paper substrate.
As the autumn chill arrives, the queen lays eggs that will hatch into fertile males and females; these non-workers will mate and the pregnant females will become next year's queens. Once the winter freeze sets in, the hive is abandoned, the future queens retreat to warm dens (either underground or in structures) and all others perish.
Back on the Farm
It's good to be back at our Littleton, Colorado, farm, if only for a week. September is always a good time to visit and, since I was last here in July, there has been a significant change. Recent rains have greened-up the "lawn" and the trees and shrubs look especially vibrant for late summer. It's been a good year for pears, apricots and crab apples but the other apple trees have a rather sparse crop. The mulberry trees have been picked clean by the robins, orioles and house finches but there's plenty of juniper berries to last the winter.
The rose of sharon and trumpet vines are still in bloom, attracting our resident hummingbirds and a few migrants from the mountains. Other visitors have included western wood pewees, Lincoln's sparrows, rufous-sided towhees, yellow warblers, western tanagers and a surprising number of blue-gray gnatcatchers. The collared doves and lesser goldfinches, first seen in July, are still hanging around, joining the usual mix of chickadees, northern flickers, mourning doves, house finches, blue jays and magpies.
A neighbor is boarding a quartet of calves on our large pasture and all of the activity seems to have evicted our resident fox. For now, the squirrels and songbirds need only fear the occasional "sharpie" that streaks through the neighborhood and the Swainson's hawks that often soar above the farm.
The rose of sharon and trumpet vines are still in bloom, attracting our resident hummingbirds and a few migrants from the mountains. Other visitors have included western wood pewees, Lincoln's sparrows, rufous-sided towhees, yellow warblers, western tanagers and a surprising number of blue-gray gnatcatchers. The collared doves and lesser goldfinches, first seen in July, are still hanging around, joining the usual mix of chickadees, northern flickers, mourning doves, house finches, blue jays and magpies.
A neighbor is boarding a quartet of calves on our large pasture and all of the activity seems to have evicted our resident fox. For now, the squirrels and songbirds need only fear the occasional "sharpie" that streaks through the neighborhood and the Swainson's hawks that often soar above the farm.
Monday, September 15, 2008
The Yellowing
After days of heavy rain, there was nothing but brilliant sunshine on my trip to Colorado today; only the distant smoke of power plants and shimmering clouds of starlings marred the deep, blue sky. A dome of high pressure had settled over the Plains, clearing the air and stifling any wind; the turbines at the Smoky Hills Wind Farm, west of Salina, were nearly stationary.
Despite the spectacular weather, wildlife was scarce on my drive along the interstate. Turkey vultures tilted above the shallows of the Missouri River floodplain, searching for victims of the deluge. Red-tailed and Swainson's hawks hunted along the highway, several herds of pronghorn grazed the High Plains near Limon and the occasional box turtle tempted fate on our concrete ribbon of death.
Most noticeable were the changing colors of the landscape. Summer greens had faded to olive, the Flint Hills tallgrass was tipped with gold and a variety of sunflowers, coneflowers and goldenrod adorned the grasslands of Missouri and Kansas. Not to be outdone, the croplands offered their seasonal gold, including fields of yellowing soybean, gold-headed sorghum and cultivated sunflowers. In eastern Colorado, yellow clumps of rabbitbrush and western goldenrod adorned the prairie and creekside cottonwoods were dappled with gold. As summer wanes, yellows paint the American West.
Despite the spectacular weather, wildlife was scarce on my drive along the interstate. Turkey vultures tilted above the shallows of the Missouri River floodplain, searching for victims of the deluge. Red-tailed and Swainson's hawks hunted along the highway, several herds of pronghorn grazed the High Plains near Limon and the occasional box turtle tempted fate on our concrete ribbon of death.
Most noticeable were the changing colors of the landscape. Summer greens had faded to olive, the Flint Hills tallgrass was tipped with gold and a variety of sunflowers, coneflowers and goldenrod adorned the grasslands of Missouri and Kansas. Not to be outdone, the croplands offered their seasonal gold, including fields of yellowing soybean, gold-headed sorghum and cultivated sunflowers. In eastern Colorado, yellow clumps of rabbitbrush and western goldenrod adorned the prairie and creekside cottonwoods were dappled with gold. As summer wanes, yellows paint the American West.
Sunday, September 14, 2008
Ike's Reign
Born two weeks ago, off the coast of Africa, Hurricane Ike ravaged several islands of the Caribbean before spinning into the Gulf of Mexico and growing into a massive, category 2 storm. Leaving a broad swath of water and wind damage across coastal Texas and Louisiana, it moved inland and brought heavy rains to northeast Texas, eastern Oklahoma and Arkansas.
Over the past twenty four hours, an approaching cold front nudged Ike to the northeast and, as of this morning, its remnant depression was centered over southeast Missouri. Here in Columbia, we received torrents of rain before the winds shifted from the north, indicating that the "backside" of Ike's circulation had arrived. Making a beeline for Chicago, Ike will leave more flooding before its reign ends over the Great Lakes region.
Though the route of these storms may seem aimless, their motion is a reflection of upper air flow which, in turn, is governed by the jet stream pattern. Once Ike entered the Gulf of Mexico, it was deflected westward by high pressure over the Southeastern U.S., causing it to strike Texas . Once inland, the storm encountered an advancing trough; this dip in the jet stream pushed Ike off to the northeast, squeezed between the approaching cold front (to its northwest) and the retreating high pressure dome (to the southeast).
Over the past twenty four hours, an approaching cold front nudged Ike to the northeast and, as of this morning, its remnant depression was centered over southeast Missouri. Here in Columbia, we received torrents of rain before the winds shifted from the north, indicating that the "backside" of Ike's circulation had arrived. Making a beeline for Chicago, Ike will leave more flooding before its reign ends over the Great Lakes region.
Though the route of these storms may seem aimless, their motion is a reflection of upper air flow which, in turn, is governed by the jet stream pattern. Once Ike entered the Gulf of Mexico, it was deflected westward by high pressure over the Southeastern U.S., causing it to strike Texas . Once inland, the storm encountered an advancing trough; this dip in the jet stream pushed Ike off to the northeast, squeezed between the approaching cold front (to its northwest) and the retreating high pressure dome (to the southeast).
Friday, September 12, 2008
Storm Surge
As hurricanes come ashore, they cause destruction via heavy rain, high winds and storm surge; the latter is often least appreciated by coastal residents and visitors. The amount of rainfall is most closely related to the forward speed of the hurricane; the slower it moves, the more rain it drops on any given area. The wind damage correlates with the strength of the hurricane; the lower the central pressure, the higher the sustained wind speed and, thus, the greater the impact on structures.
The storm surge refers to the buildup of ocean water ahead of the storm. As the hurricane comes ashore, it acts like a giant plow, forcing a broad river of water toward the coast; this phenomenon is greatest to the right of the storm's center, reflecting the counter-clockwise motion of the surface winds. The threat from storm surge is related to the size of the hurricane and to the region's topography; flat coastal plains that lie along shallow bays are especially vulnerable.
If the coastal water is deep and the impact area broad, the plowed water can displace downward and outward, minimizing the surge; however, if the sea is shallow and the topography funnels the flow into a bay or river valley, the building surge has no escape and a devastating flood develops.
Hurricane Ike, currently a category 2 storm, is forecast to strike the northern coast of Texas tonight. Gulf waters are relatively shallow in that area and coastal bays to the right (north) of the landfall will experience the greatest inflow of water. A storm surge of 20 feet is expected; any land (and structures) below that elevation will be underwater.
The storm surge refers to the buildup of ocean water ahead of the storm. As the hurricane comes ashore, it acts like a giant plow, forcing a broad river of water toward the coast; this phenomenon is greatest to the right of the storm's center, reflecting the counter-clockwise motion of the surface winds. The threat from storm surge is related to the size of the hurricane and to the region's topography; flat coastal plains that lie along shallow bays are especially vulnerable.
If the coastal water is deep and the impact area broad, the plowed water can displace downward and outward, minimizing the surge; however, if the sea is shallow and the topography funnels the flow into a bay or river valley, the building surge has no escape and a devastating flood develops.
Hurricane Ike, currently a category 2 storm, is forecast to strike the northern coast of Texas tonight. Gulf waters are relatively shallow in that area and coastal bays to the right (north) of the landfall will experience the greatest inflow of water. A storm surge of 20 feet is expected; any land (and structures) below that elevation will be underwater.
Thursday, September 11, 2008
Earthquake Central
Looking at a map of the North Pacific, one finds that the Aleutian Chain of Alaska is continuous with other islands off the east coast of Asia; the latter include the islands of Japan. This curving line of islands marks the southern edge of the North American Plate, which extends northward to include eastern Siberia; south of Tokyo, the Japanese islands lie on the eastern edge of the Eurasian Plate. Indeed, Japan lies at the intersection of four major tectonic plates: the North American, Eurasian, Philippine and Pacific Plates.
The North American and Eurasian Plates are colliding in the center of Honshu, Japan's largest island; though the exact position of this collision zone remains controversial, most geologists place it just southwest of Tokyo. The Philippine Plate is subducting beneath the Eurasian Plate along the southern margin of Japan while the Pacific Plate is subducting beneath the North American Plate along the eastern edge of this island nation. Finally, to the southeast, the Philippine and Pacific Plates are scraping against one another.
All of this tectonic activity makes Japan very susceptible to earthquakes; today's quake was off the east coast of Hokkaido (Japan's large, northern island), reflecting a release of pressure along the Pacific-North American margin. Volcanism along both of the subduction zones produced the islands of Japan and, in concert with this tectonic activity, poses an ongoing threat to the country's residents.
The North American and Eurasian Plates are colliding in the center of Honshu, Japan's largest island; though the exact position of this collision zone remains controversial, most geologists place it just southwest of Tokyo. The Philippine Plate is subducting beneath the Eurasian Plate along the southern margin of Japan while the Pacific Plate is subducting beneath the North American Plate along the eastern edge of this island nation. Finally, to the southeast, the Philippine and Pacific Plates are scraping against one another.
All of this tectonic activity makes Japan very susceptible to earthquakes; today's quake was off the east coast of Hokkaido (Japan's large, northern island), reflecting a release of pressure along the Pacific-North American margin. Volcanism along both of the subduction zones produced the islands of Japan and, in concert with this tectonic activity, poses an ongoing threat to the country's residents.
A Balmy Flow
The same high pressure dome that is deflecting Hurricane Ike toward Texas is pulling warm, moist air into the Midwest. Unlike the cool, dry air of this past week, this balmy air mass resists heating and cooling; our highs and lows of the next two days will be within 6 or 7 degrees F of each other while temperatures spanned a range of 20-25 degrees F when the air was dry and the skies were clear.
Our overnight low was 67, producing a frenzy of insect calls more typical of mid August. Just ten days short of the equinox, these crickets and katydids feel the instinctual pressure to breed before the autumn chill ends their reign. Many humans, disdainful of the cold, also welcome this balmy flow, a short-lived respite from the march toward winter.
Showers developed this morning and, as the next cold front approaches, the rain will intensify tonight. By the weekend, autumn will reclaim the Heartland.
Our overnight low was 67, producing a frenzy of insect calls more typical of mid August. Just ten days short of the equinox, these crickets and katydids feel the instinctual pressure to breed before the autumn chill ends their reign. Many humans, disdainful of the cold, also welcome this balmy flow, a short-lived respite from the march toward winter.
Showers developed this morning and, as the next cold front approaches, the rain will intensify tonight. By the weekend, autumn will reclaim the Heartland.
Tuesday, September 9, 2008
September in Colorado
Though October gets the nod in the Midwest, September is my favorite month in Colorado. Mild days and cool nights typify the weather and snow dusts the high peaks, heralding a change in the seasons. Out on the Eastern Plains, large flocks of gulls, waders, shorebirds, cormorants, pelicans and early waterfowl gather at the larger reservoirs, preparing to migrate to southern climes.
Songbirds are moving south along the foothills while, in the higher mountains, some species are preparing their descent to lower elevations for the winter. In like manner, Colorado's elk begin their journey to mountain valleys and foothill meadows and, by the end of the month, the bugles of the adult bulls echo through the high country. The quaking aspen start to turn by the middle of the month, producing shimmering blankets of gold as September wanes.
Best of all, the summer crowds have dispersed and hikers can enjoy this mountain splendor in relative solitude. Glorious weather, spectacular scenery, abundant wildlife and an escape from social turmoil...what else could a naturalist want?
Songbirds are moving south along the foothills while, in the higher mountains, some species are preparing their descent to lower elevations for the winter. In like manner, Colorado's elk begin their journey to mountain valleys and foothill meadows and, by the end of the month, the bugles of the adult bulls echo through the high country. The quaking aspen start to turn by the middle of the month, producing shimmering blankets of gold as September wanes.
Best of all, the summer crowds have dispersed and hikers can enjoy this mountain splendor in relative solitude. Glorious weather, spectacular scenery, abundant wildlife and an escape from social turmoil...what else could a naturalist want?
Monday, September 8, 2008
Harvest Loon
September is usually a good time to visit Eagle Bluffs Conservation Area, southwest of Columbia. The songbird migration has begun, shorebirds are peaking, blue-winged teal are beginning to arrive and large flocks of white pelicans and great egrets congregate there before heading south. Looking forward to this annual spectacle, I headed down to the refuge last evening.
Entering the preserve, I found a large number of turkey vultures roosting on the transmission towers and spotted a lone bald eagle flying above the Missouri. A pair of white-tailed deer bolted for the woods as I approached and cottontails scampered from the roadway at every bend. Other than those expected encounters, the refuge was remarkably quiet. Green-backed herons were well represented and the occasional great blue heron stalked the shallows; but only a couple of great egrets flapped across the wetlands and, other than a lone coot, the only waterfowl were a group of decoys placed by a hunter. Only the red-winged blackbirds, gathering in their huge, autumn flocks, were abundant.
Disappointed by the low turnout, I was making a final loop through the flooded fields when I caught sight of a large, black and white bird flying toward the river; it was a common loon! A variety of loons migrate through Missouri and some winter on the large lakes, especially across the southern half of the State. But seeing one in early September, especially on an evening when more common birds were scarce, was an unexpected treat. Nature always comes through in one way or another; you just have to get out there!
Entering the preserve, I found a large number of turkey vultures roosting on the transmission towers and spotted a lone bald eagle flying above the Missouri. A pair of white-tailed deer bolted for the woods as I approached and cottontails scampered from the roadway at every bend. Other than those expected encounters, the refuge was remarkably quiet. Green-backed herons were well represented and the occasional great blue heron stalked the shallows; but only a couple of great egrets flapped across the wetlands and, other than a lone coot, the only waterfowl were a group of decoys placed by a hunter. Only the red-winged blackbirds, gathering in their huge, autumn flocks, were abundant.
Disappointed by the low turnout, I was making a final loop through the flooded fields when I caught sight of a large, black and white bird flying toward the river; it was a common loon! A variety of loons migrate through Missouri and some winter on the large lakes, especially across the southern half of the State. But seeing one in early September, especially on an evening when more common birds were scarce, was an unexpected treat. Nature always comes through in one way or another; you just have to get out there!
Sunday, September 7, 2008
Hurricane Season
The Atlantic Hurricane Season begins on June 1 and ends by mid November; the second week in September generally represents the peak of hurricane development. Early in the season, tropical depressions (the precursors of tropical storms and hurricanes) usually develop from disturbances over the warm waters of the Caribbean and Gulf of Mexico. If not aborted by strong, upper-level winds or by interaction with areas of inversion (sinking, dry air), these isolated depressions feed on the heat and humidity of the tropical atmosphere, develop rotating clusters of thunderstorms and may give rise to a tropical storm; the latter becomes a hurricane if its peak, sustained winds reach 74 mph.
By mid summer, the easterly African jet stream begins to carry waves of low pressure into the tropical Atlantic. Drifting westward, these waves may progress to tropical depressions and thence to tropical storms and hurricanes. In many cases, cold fronts, moving east off the coast of North America, deflect these storms to the north and they die over the cooler waters of the North Atlantic. If not deflected by fronts or torn apart by upper level winds, the storms continue westward, threatening islands of the Caribbean or the Southeast Coast of the U.S.; in some cases, they move into the Gulf of Mexico.
Today, Hurricane Ike, a category 4 storm, is poised to strike eastern Cuba. It's strength will likely diminish over the mountainous landscape of that island (primarily due to the loss of its tropical water heat source) but the remnant circulation is expected to emerge over the Gulf of Mexico, regain strength and move toward the northern or western Gulf Coast. Then again, hurricanes are notoriously unpredictable; as they say, stay tuned!
By mid summer, the easterly African jet stream begins to carry waves of low pressure into the tropical Atlantic. Drifting westward, these waves may progress to tropical depressions and thence to tropical storms and hurricanes. In many cases, cold fronts, moving east off the coast of North America, deflect these storms to the north and they die over the cooler waters of the North Atlantic. If not deflected by fronts or torn apart by upper level winds, the storms continue westward, threatening islands of the Caribbean or the Southeast Coast of the U.S.; in some cases, they move into the Gulf of Mexico.
Today, Hurricane Ike, a category 4 storm, is poised to strike eastern Cuba. It's strength will likely diminish over the mountainous landscape of that island (primarily due to the loss of its tropical water heat source) but the remnant circulation is expected to emerge over the Gulf of Mexico, regain strength and move toward the northern or western Gulf Coast. Then again, hurricanes are notoriously unpredictable; as they say, stay tuned!
Saturday, September 6, 2008
Man, Intelligence and Knowledge
When man first appeared, 125,000 years ago, he had the same intellectual capacity that we have today. Though, like any human trait, intelligence varies between individuals, all healthy members of our species are equipped with the brain power to learn, to understand and to communicate; of course, some take more advantage of this potential than do others.
Our human ancestors used their intelligence to understand the nature of their environment, to gather food, to avoid danger and to protect themselves from the elements. Over time, experience and experimentation have greatly increased our knowledge but the innate intelligence of our species has not changed. Though we have the same intellectual capacity as those first humans who spread from Africa, the combined effects of curiosity, exploration, communication and hard work (mental and physical) have led to an exponential growth of our knowledge. Today's average high school student has a better understanding of many scientific issues than did the "great minds" of past centuries; human knowledge is a group effort to which the individual both subscribes and contributes.
Of course, the acquisition and communication of knowledge can pose a threat to some groups and, throughout history, they have attempted to block our progress; politicians, dictators and religious leaders come to mind. If we don't destroy our planet first, evolution will eventually free us from those human constraints.
Our human ancestors used their intelligence to understand the nature of their environment, to gather food, to avoid danger and to protect themselves from the elements. Over time, experience and experimentation have greatly increased our knowledge but the innate intelligence of our species has not changed. Though we have the same intellectual capacity as those first humans who spread from Africa, the combined effects of curiosity, exploration, communication and hard work (mental and physical) have led to an exponential growth of our knowledge. Today's average high school student has a better understanding of many scientific issues than did the "great minds" of past centuries; human knowledge is a group effort to which the individual both subscribes and contributes.
Of course, the acquisition and communication of knowledge can pose a threat to some groups and, throughout history, they have attempted to block our progress; politicians, dictators and religious leaders come to mind. If we don't destroy our planet first, evolution will eventually free us from those human constraints.
Friday, September 5, 2008
Desert Formation
Deserts are generally defined as geographic regions that receive an annual average precipitation of 10 inches or less. Many factors combine to produce such a low level of precipitation but three conditions tend to predominate.
Most of the deserts on this planet are aligned along the Tropics of Cancer and Capricorn where persistent high pressure zones cause the air to sink; sinking air compresses, dries out and heats up, creating an atmosphere of low humidity and sparse cloud cover. The dry air, abundant sunshine and radiant nocturnal cooling lead to wide swings in temperature throughout the 24-hour cycle; hot, sunny days and chilly, clear nights characterize these desert regions for most of the year. These conditions are hostile to most species of vegetation, minimizing plant transpiration and further reducing the natural processes that humidify the atmosphere.
Similar climatological factors often lead to desert formation on the lee side of mountain ranges. Prevailing winds carry moisture-laden air into the mountains where it is forced to rise and condense, dropping most of its rain and snow on the windward side of the divide; moving beyond the summit of the range, the air descends, heats up and dries out. The deserts of eastern Oregon, Nevada and southeastern California, lying east of the Sierra Nevada, are classic examples of mountain-induced desert formation.
Finally, a couple of the driest deserts on Earth, the Atacama of Chile and the Namib of West Africa, lie along western coastlines bordered by cold ocean currents. Prevailing winds reach these deserts from the east, having crossed the girth of the Continent and mountain ranges along the way; what little moisture remains is lost as the air descends toward the shore. Occasional disruptions in this flow may allow westerlies to sweep in from the ocean but their moisture precipitates as the air crosses the cold waters of the sea; only a shroud of sea fog reaches these coastal deserts, offering droplets of water to the parched landscape.
Most of the deserts on this planet are aligned along the Tropics of Cancer and Capricorn where persistent high pressure zones cause the air to sink; sinking air compresses, dries out and heats up, creating an atmosphere of low humidity and sparse cloud cover. The dry air, abundant sunshine and radiant nocturnal cooling lead to wide swings in temperature throughout the 24-hour cycle; hot, sunny days and chilly, clear nights characterize these desert regions for most of the year. These conditions are hostile to most species of vegetation, minimizing plant transpiration and further reducing the natural processes that humidify the atmosphere.
Similar climatological factors often lead to desert formation on the lee side of mountain ranges. Prevailing winds carry moisture-laden air into the mountains where it is forced to rise and condense, dropping most of its rain and snow on the windward side of the divide; moving beyond the summit of the range, the air descends, heats up and dries out. The deserts of eastern Oregon, Nevada and southeastern California, lying east of the Sierra Nevada, are classic examples of mountain-induced desert formation.
Finally, a couple of the driest deserts on Earth, the Atacama of Chile and the Namib of West Africa, lie along western coastlines bordered by cold ocean currents. Prevailing winds reach these deserts from the east, having crossed the girth of the Continent and mountain ranges along the way; what little moisture remains is lost as the air descends toward the shore. Occasional disruptions in this flow may allow westerlies to sweep in from the ocean but their moisture precipitates as the air crosses the cold waters of the sea; only a shroud of sea fog reaches these coastal deserts, offering droplets of water to the parched landscape.
Wednesday, September 3, 2008
Gustav Visits Missouri
After ravaging much of Louisiana, Hurricane Gustav, now a Tropical Depression is centered over southwest Arkansas. Its counter-clockwise circulation is sweeping copious moisture into the Heartland, just in time to meet a potent cold front that is dropping through the Midwest. Combine these meteorologic events and you get continuous, flooding rains.
Here in central Missouri, light rain developed by dawn and waves of heavier precipitation have occurred throughout the day. A mild north wind (we are now behind the front) has kept the temperature in the lower sixties, quite a contrast from the summer heat of this past week. As the remnants of Gustav move northeastward along the front, our rain is expected to increase, totalling a couple of inches overnight and just as much tomorrow.
By the weekend, the cold front should be far enough east to keep us out of the rain; sunny skies and mild, dry air are forecast. Hurricane Hanna should be striking the Southeast Coast about then!
Here in central Missouri, light rain developed by dawn and waves of heavier precipitation have occurred throughout the day. A mild north wind (we are now behind the front) has kept the temperature in the lower sixties, quite a contrast from the summer heat of this past week. As the remnants of Gustav move northeastward along the front, our rain is expected to increase, totalling a couple of inches overnight and just as much tomorrow.
By the weekend, the cold front should be far enough east to keep us out of the rain; sunny skies and mild, dry air are forecast. Hurricane Hanna should be striking the Southeast Coast about then!
Tuesday, September 2, 2008
Sheltowee Trace Trail
As summer gives way to the glorious season of fall, hikers across the country search for new adventures. One of the better trails in the eastern U.S. is the Sheltowee Trace Trail, which winds across the Appalachian Plateau from Pickett State Park, in Tennessee, to Rowan County, Kentucky, north of Morehead. Running the entire length of Daniel Boone National Forest, the 257-mile route (Forest Trail 100) was named in honor of Kentucky's famous explorer; Sheltowee, which means Big Turtle, was the name given to Daniel Boone by local Native Americans.
On its course through Kentucky, the Sheltowee Trace crosses the Big South Fork National Recreation Area, winds past Cumberland Falls and skirts the north shore of Laurel River Lake. North of McKee, the trail curves along a scenic, rock-walled gorge and then drops to the Turkey Foot Recreation Area, on the War Branch of Station Camp Creek. Heading north, it eventually enters Natural Bridge State Resort Park, one of the most spectacular sites in Kentucky. Just beyond this scenic refuge, the trail crosses the wilds of Red River Gorge, a camping and backpacking destination for many Easterners. Finally, nearing I-64, the Sheltowee Trace connects a series of wildlife areas west and north of Cave Run Lake, on the Licking River.
Almost any section of the trail offers a scenic day hike. Those planning multi-day excursions should check with Daniel Boone National Forest rangers for back-country permits and camping information.
On its course through Kentucky, the Sheltowee Trace crosses the Big South Fork National Recreation Area, winds past Cumberland Falls and skirts the north shore of Laurel River Lake. North of McKee, the trail curves along a scenic, rock-walled gorge and then drops to the Turkey Foot Recreation Area, on the War Branch of Station Camp Creek. Heading north, it eventually enters Natural Bridge State Resort Park, one of the most spectacular sites in Kentucky. Just beyond this scenic refuge, the trail crosses the wilds of Red River Gorge, a camping and backpacking destination for many Easterners. Finally, nearing I-64, the Sheltowee Trace connects a series of wildlife areas west and north of Cave Run Lake, on the Licking River.
Almost any section of the trail offers a scenic day hike. Those planning multi-day excursions should check with Daniel Boone National Forest rangers for back-country permits and camping information.
Monday, September 1, 2008
Celebrity Coast
Everyone who's anyone in the American media has gathered along the Louisiana coast to stand in the wind and rain as Hurricane Gustav comes ashore. Of course, the political fiasco that followed Katrina is part of their motivation but one would think that local news and weather personnel could provide the storm coverage. Perhaps these gods of American culture are convinced that we, the adoring American public, can only believe what they, the American media celebrities, have to report.
With all due respect to the suffering of Louisiana residents, it is time that we focus attention on the futility of living on floodplains and in areas protected by levees. Decades without a major storm or flood allow us to become complacent; we make assumptions based on what we have observed during our brief, human lives, an instant in natural history. Then, two major hurricanes strike within three years and the toll on society, measured in both human lives and financial costs, is staggering.
Hopefully, once they dry out, our media celebrities will descend on Washington to focus on policies that feed these tragedies.
With all due respect to the suffering of Louisiana residents, it is time that we focus attention on the futility of living on floodplains and in areas protected by levees. Decades without a major storm or flood allow us to become complacent; we make assumptions based on what we have observed during our brief, human lives, an instant in natural history. Then, two major hurricanes strike within three years and the toll on society, measured in both human lives and financial costs, is staggering.
Hopefully, once they dry out, our media celebrities will descend on Washington to focus on policies that feed these tragedies.
Subscribe to:
Posts (Atom)