Contrail Question

I'll start by saying that after a lot of thought, I've decided that I don't believe in "chemtrails". I do, however, wonder about the determining factors for upper atmospheric temperatures.

For me, like many others when first introduced to the "chemtrail" theory, it was the fact that some trails lingered in the sky while other dissipated almost immediately, that led to some suspicion. I didn't even look it up before considering that it probably had something to do with how hot or cold it is up there made the difference, which was confirmed upon doing a little bit of reading.

That said, I've recently taken notice that I see lingering trails on very cold days, as well as very warm days. I realize that there is a significant difference between how warm/cool it is on the surface of the earth compared to up in the sky, but is there really no correlation between the two at all? How can it be hot on the ground, but below freezing in the sky?

Originally posted by Jack Squat
How can it be hot on the ground, but below freezing in the sky?

The sun's heat doesn't warm the air, it warms the water and land, which then warms the air around it.

The atmosphere is much thinner at higher altitudes, thus holding less warmth. There is also less oxygen and that's why jetliners that travel at that altitude carry oxygen for breathing in case of pressure loss.

reply to post by Jack Squat


There's something of a correlation, the temperature falls at fairly constant rate as you rise in altitude. This rate is known as the lapse rate:

www.britannica.com...

So the hotter it is on the ground, the higher you have to go before you get to -40 degrees, where persistent contrails will form.

However, since jets fly at all altitudes between 25,000 and 45,000 feet, then there's generally always some altitude that is cold enough.

reply to post by Adyta


Not true. That's why there are warm fronts and cold fronts that bring with them either warm air or cold air. Meteorology 101.

Chemtrails definitely exist.

So do idiots.

Originally posted by vermonster
Chemtrails definitely exist.

So do idiots.

"Chemtrails" can't "definitely" exist without any scientific evidence. But, you are right about one thing: idiots definitely exist.

Here is how the atmosphere can be warmer on the suface than high in the sky. Study the Green House effect and that should give a pretty good reason why.

The sun emits heat radiation that a small portion of which is able to pass through the atmosphere and heat the atmosphere and surface. Once the the surface is heated by the heat radiation the earth then emits the same heat back through the atmosphere. Now the atmosphere is composed of layers each varrying in density and pressure. The layers that are more dense and have a higher pressure are closer to the surface do to gravitation pull on the molecules. It's this density and pressure that allows that surface atmosphere to be warmer than higher atmospheric layers. The high dense packed atmosphere at the surface slows earth's emision of heat radiation and acts as an insulator. The higher less dense atmoshere allows the heat to escape more quickly making it cooler. Humidity also plays a role in the density of the atmosphere. This is also the reason why mountains have snow on their peaks.

So what would cause it to be warm enough up there to ensure that contrails wouldn't linger?

Originally posted by Jack Squat
So what would cause it to be warm enough up there to ensure that contrails wouldn't linger?

"up there" is a bit vague. Basically if it's above -40, then persistent contrails are unlikely to form. But it's always that cold at some altitude. The question then becomes how humid it is. You need about 70% relative humidity (at the -40 and colder altitudes.

reply to post by Jack Squat


Same reason. The atmosphere isn't uniformly the same temperature. One part of the upper atmosphere is warmer or colder than another part of the upper atmosphere. Each changing everyday. Clouds behave the same way. Some linger longer than others depending on the current temperature and pressure.

So it's random day by day, much like the weather on the surface? Also, thanks for the info guys.

yup pretty much.

Temperature on the ground is predictable... we have seasons, and meteorologists correctly predict the weather all the time. Are upper atmospheric temperatures predictable?

Originally posted by Jack Squat
I'll start by saying that after a lot of thought, I've decided that I don't believe in "chemtrails". I do, however, wonder about the determining factors for upper atmospheric temperatures.

For me, like many others when first introduced to the "chemtrail" theory, it was the fact that some trails lingered in the sky while other dissipated almost immediately, that led to some suspicion. I didn't even look it up before considering that it probably had something to do with how hot or cold it is up there made the difference, which was confirmed upon doing a little bit of reading.

That said, I've recently taken notice that I see lingering trails on very cold days, as well as very warm days. I realize that there is a significant difference between how warm/cool it is on the surface of the earth compared to up in the sky, but is there really no correlation between the two at all? How can it be hot on the ground, but below freezing in the sky?

edit on 12-5-2011 by Jack Squat because: (no reason given)

I am glad to see you asking the question though. Many of the "chemtrailers" already just assume that hot on the ground means hot up high, or dry down below means dry up high, but I do notice that you do not consider yourself one of them anymore

The lapse (cooling rate) in the lower atmosphere is about 3-4 degrees F, per 1000 ft of altitude, up to around 35,000 ft. The temperature is virtually always below 0 F from 24,000 ft on up, regardless of the time of the year. So its usually always going to be around -60F at 35,000 ft or so. Doesnt matter if its over Phoenix AZ or the Saharan desert, the altitudes that jet aircraft cruise at, will be below freezing.

The lapse rate can vary on different atmospheric factors so it is not a constant value, and as you get above 60,000 ft or so, the atmosphere begans to warm up again.

Originally posted by Jack Squat
Temperature on the ground is predictable... we have seasons, and meteorologists correctly predict the weather all the time. Are upper atmospheric temperatures predictable?

Yes, in fact the upper air weather is predicted along with the ground level weather, as it's all interlinked, so the computers have to model the whole thing to get accurate predications.

Here's a site that gives weather forecasts for various locations and gives the different wind speeds and temperatures at various altitudes:

www.usairnet.com...

Originally posted by Uncinus
Here's a site that gives weather forecasts for various locations and gives the different wind speeds and temperatures at various altitudes:

www.usairnet.com...

So theoretically a person could predict what areas will have trails using that site, no?

reply to post by Jack Squat


They do/did during war time. I have seen a web link a while ago about contrail predicting for Europe during ww2.

Originally posted by Jack Squat

Originally posted by Uncinus
Here's a site that gives weather forecasts for various locations and gives the different wind speeds and temperatures at various altitudes:

www.usairnet.com...

So theoretically a person could predict what areas will have trails using that site, no?

Not really, as you need the humidity. However you could use this site, which is specifically for forecasting contrails.

www-angler.larc.nasa.gov...

Originally posted by Uncinus

Not really, as you need the humidity. However you could use this site, which is specifically for forecasting contrails.

www-angler.larc.nasa.gov...

So if that website is even moderately accurate, how can "Chemtrail" believers even debate the subject?