 . 24/7 Space News .  Urban heat - not a myth, and worst where
it's wet by Staff Writers Yale CA (SPX) Jul 11, 2014  This NASA
image illustrates the temperature differential between the city
of Providence and the surrounding region. Image courtesy NASA
Earth Observatory.   In an analysis of 65 cities across North
America, researchers found that variation in how efficiently
urban areas release heat back into the lower atmosphere -
through the process of convection - is the dominant factor in
the daytime UHI effect. This finding challenges a long-held
belief that the phenomenon is driven principally by diminished
evaporative cooling through the loss of vegetation.  The effects
of impaired "convective efficiency" are particularly acute in
wet climates, the researchers say. In cities such as Atlanta,
Georgia, and Nashville, Tennessee, this factor alone contributes
a 3-degree C rise in average daytime temperatures, according to
the study, published July 10 in the journal Nature.  The
phenomenon could have profound