Summer nights are warmer in America

Thursday, August 03, 2006
From the AP:

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...


terrye said...

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.


Syl said...

Sounds about right to me, Terrye.

crosspatch said...

Water vapor is so much better of a greenhouse gas that once you increase the water in the atmosphere even a little bit, increasing CO2 by 10x won't have any impact. Water vapor completely swamps CO2 pretty early in the system.

The last interglacial ... the warm period before the last ice age ... was warmer than this one has been. Trees grew hundreds of miles further North in what is now tundra. We weren't burning oil then.

There have been two and possibly three periods during THIS interglacial that were warmer than now. We may now have fully recovered from the Little Ice Age, a cool period of this interglacial that we started to recover from in the late 1700's and early 1800's.

Thermometers were invented at about the time the climate started to recover from the LIA making it expected to see warming temperature records over time.

Glacial retreat in the Alps is exposing tree trunks. Carbon dating of these trees show that they died toward the end of the Roman Empire leading to speculation that periods such as the expansion of the Roman Empire was in part helped by a warming climate, longer growing seasons, and improved harvests along with easier communications across the Alps. The fall of the empire and other events such as the Dark Ages might correlate with periods of cooling when there would have been difficulty crossing the Alps, shorter growing seasons, failed crops due to early/late frost and famine induced unrest and migration of outsiders seeking better conditions.

The "hocky stick" graph produced by Mann et al for the UN has been shown to be a fabrication based on cherry picking data and flawed mathematical functions. There is no reliable evidence to show that the rate of global warming is increasing.

Warmer periods result in better conditions for humans and cooler periods have been disasters. One of the warmest periods in this interglacial was at about the time the Mesopotamians were creating this cool idea called civilization.

The Holocene Optimum was much warmer than it is now, was during this interglacia, and sea levels were higher.

Climate is almost always changing, either warming, cooling, or oscillating around an average. It is rarely stable for long periods of geological time.

Gore is full of crap.

amba said...

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.