Is it colder at the approach end of the runway?

Robert M. Gary wrote:

I live near Sacramento where we have long periods of 100+ degree
temps. The gov't has been doing research here on the affect of asphalt
and roofs (not sure why) on temps. They fly a plane overhead in the
afternoon with sensitive heat detecting equipment. They seem to
believe the city is much hotter simply because of the pavement and the
roofs.


Don't know why they'd be studying it in Sacramento. Here in Phoenix it has
long been known as the "Heat Island". Basically, asphalt, roofs and concrete
absorb much more heat than dirt or grass. The result is that this excess
heat is liberated slowly after the sun goes down and raises the overnight low
temperature in populated areas.

If you live in a rapidly expanding desert town long enough, it's easy to
see. When I moved here, there were about 1.5 million people in the metro
area. During the hottest part of the summer, overnight low temperatures
stayed in the mid to upper 80s. Nowadays, we have about 4 million people and
the overnight lows stay in the low to mid 90s at the peak of summer. Daytime
temperatures haven't shown any corresponding increase.

John Galban=====N4BQ (PA28-180)

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