After hearing about the extreme heat across the Desert Southwest over the past week, one might wonder why we never see similar temperatures in Florida. There are multiple reasons why tempera-tures of 110F or above are generally limited to desert areas.
Deserts develop in regions with sinking air and/or where regional mountains create both rain shadows and downslope winds. As air sinks, it compresses, dries out and heats up. Dry air is more dense than humid air and is thus capable of reaching higher temperatures. Adding to these factors, deserts are often cut off from precipitation by mountains on their windward side; rain and snow are minimal and cloudless skies intensify the solar heating. Lack of precipitation also leads to sparse vegetation, causing the rocks, soil and concrete to absorb heat through the day, radiating it back to the lower atmosphere day and night.
When local weather patterns remain stable for an extended period, the heat can build to levels we have seen this week (highs of 116-118 in Phoenix and Las Vegas). Only a strong cold front or monsoon moisture will break this cycle of dryness and heat.
