America in recent years has been sweltering through three times more than its normal share of extra-hot summer nights, government weather records show. And that is a particularly dangerous trend....Some scientists say the trend is a sign of manmade global warming....A top federal research meteorologist said he "almost fell out of my chair" when he looked over U.S. night minimum temperature records over the past 96 years and saw the skyrocketing trend of hot summer nights....One reason global warming is suspected in summer-night temperatures is that daytime air pollution slightly counteracts warming but is not as prevalent at night, said Bill Chameides, a climate scientist for the advocacy group Environmental Defense.
Okay. Fine. BUT...
I believe warmer nights are due to water vapor. The most major 'greenhouse gas' of all.
The air temperature does not fall below the dewpoint. So if your dewpoint is higher than normal, your nightime lows will also be higher. And if the climate is heating up, more water will evaporate into the atmosphere and raise the dewpoints. Or, even without or with only very slight global warming, a shift in climate and oceanic patterns could be affecting the amount of evaporation into the atmosphere in certain areas of the earth.
One thing my local NWS guy said in one of the weather 'discussions' I read daily is that though the current heatwave isn't really all that unusual historically, the higher dewpoints are.
Just saying...
3 comments:
This may or may not be pertinent, but in Oklahoma after the Dust Bowl the decision was made that the state was not going to dry up and blow away again. So they made lakes, lots of them and now there is more evaperation in Oklahoma and some people say that has increased the humidity and so the night temps are higher because the air is not as arid.
Maybe.....
Sounds about right to me, Terrye.
In large cities, warmer nights are at least partly due to the fact that people keep their air conditioners on, pumping heated air out into the ambient air. Vicious cycle.
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