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My wife and I are 63 yrs of age and grew up here and in Greensboro, N.C. We both distinctly remember that in summertime the hottest time of day was reported to be at noon...now it is usually late afternoon. We understand the greenhouse effect, but don't understand why 50 years ago this was reported to be at noon, and yes, we understand that the earth heats up during the day. Why was it different 50 years ago?

Posted February 14, 2007

MIKE MOSS SAYS:     Dan,    It may have been that people considered noon or thereabouts to "seem" the hottest of the day in the summer, since at that time of day the sun is near it's highest point in the sky and its rays are most direct and intense. In addition, there are times in the summer when convective mixing caused by heating of the surface will bring somewhat drier air down to ground level as the day wears on, reducing the combination of heat and humidity a bit by mid-afternoon so that it feels a little more comfortable even though the temperature continues to climb some. However, I'm pretty sure if we could go back and check hourly readings from the Greensboro area for those time periods, we would find that the highest air temperature of the day on most summer afternoons (barring an early afternoon thunderstorm or rain shower) would occur between about 3 and 6 pm. Even though the sun's rays are most intense around noon (more like 1 pm in daylight saving time) they remain strong enough to offset loss of heat by outgoing terrestrial radiation until fairly late in the afternoon. At that time, as the sun sinks lower in the sky, the outgoing radiation and heat loss begins to exceed the incoming solar radiation and the temperature starts to drop off again.

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