The exhaust trails of jet planes can appear like wires that crisscross the sky like a chain link fence. Sometimes they look like a trail of cotton balls. Other times they’re nearly invisible.
Given the variety and peculiarity of these trails, it’s no wonder we often get calls here at weather office asking, “Is there a new kind of plane?” or “Do you think they’re spreading chemicals?”
Conspiracy theorists who believe they witness a deliberate spread of chemicals call them chemtrails.
And no, I don’t believe this theory. I think they're really just water vapor (or a man-made cloud). Clouds come in many shapes, sizes and colors. The type of cloud in our sky (if any at all) has to do with the height of the cloud, the temperature profile of the atmosphere, humidity, horizontal and vertical movement of air, the angle of sunlight, and even the angle by which it’s viewed. Meteorologists classify clouds into many different categories. It seems there are endless subcategories, and every so often new kinds of clouds are still discovered.
http://news.nationalgeographic.com/news/2009/06/photogalleries/new-cloud-pictures/
Sometimes different types of clouds look so different, it’s easy to forget they’re all made of the same thing – water.
Jet planes have always created contrails or condensation trails. (Condensation is the name for water vapor that’s turned into liquid water.)
You can see condensation in your breath on a cold day. It’s very cold high up in the atmosphere and jet engines get very hot so this is one way to understand how contrails are formed.
A jet engine also by its very nature pressurizes the air that flows through it. The pressurization and depressurization forces water vapor in the air to condense, even if there’s very little of it. The process of freeze-drying foods has less to do with temperature than it has to do with pressure.
All the different factors that cause natural clouds to take different shapes and forms are present for these man-made clouds, too. This is why they regularly look different on different days.
With contrails, there’s always engine exhaust mixed in, so they’re not as clean of a white color as other clouds in the sky. Like other fossil fuels, you’re going to get water vapor, carbon dioxide, carbon monoxide, various other hydrocarbons, sulfurs and nitrogen oxides. (I’m actually not sure if the NOx is considered “smog” that far up in the sky… something I’ll have to look into.) Plus, shadowing and refraction (that darken thunderstorm rains and color our sunsets) are different in different types of clouds. The ice or water droplets are of different shapes, sizes and mixtures.
If there were a secret operation to spread chemicals at work, wind speeds are way too fast at cloud-level for any of those chemicals to fall to the ground over which the trails are spotted. As a means of spreading chemicals it seems to me neither practical nor economical.
To deliver chemicals to the ground, you need to be close to the ground. It’s one reason crop dusting aircraft are slower, lower-flying types of planes.
There are military uses (from obstructing visibility to delivering poisons) so the idea of chemtrails does have real basis. But these all must fly near the ground to directly deliver an aerosol. For something released so high in the atmosphere to impact us here on the ground it would have to be super powerful (because it’s going to diffuse over a chunk of the planet). It could take days or weeks to fall from the sky so it would have to have an extreme half-life, too. This would make it tough to keep secret because such a long-lasting chemical would be available to sample in air, water and soil.
There are few things (outside of radioactive substances) that can do this.
Wind speeds high in the atmosphere can be hundreds of miles per hour.
If winds up there were the same as they are here on the ground, contrails from the thousands of flights that pass over California every day would end up completely filling the sky. There are some 60,000 flights over the U.S. every day.
So, even if the chemtrail conspiracy theory was true, any chemicals we see in our skies won’t fall on us. When spotting suspicious trails in our skies, one should look for the purported effects (violence, illness, kindness, zombies, etc.) downwind in places Nevada, Arizona, or Colorado. Jetstream maps show the speed and direction of the winds at high levels of the atmosphere. Charts produced daily by weather balloons show exactly how fast winds are moving at different levels of the atmosphere. They can also tell how fast air is mixing up and down.
Even better, you can find the contrails you see in the sky on visible satellite images. Play a time-loop and you can watch them travel (intact) hundreds of miles. Those you see over Fresno quickly drift East.
http://cimss.ssec.wisc.edu/wxwise/class/CONTRL.mpg
This example is a past recording. Use the slider bar to play this 3-hour loop slow enough to see the individual contrails. The dark spot is Lake Michigan. Chicago’s O’Hare is a particularly busy airport.
You can get current imagery here: http://bit.ly/IXpu4I Experiment with the different wavelengths and filters. My experience is that specialized products (like contrail or fog algorithms) don’t work nearly as well as plain visible.
The best resolution comes from satellites that orbit closest to Earth. Their field of view is only a few states wide (as opposed to an entire continent) so most are polar-orbiters.
My favorite is TERRA (which technically is in a sun-synchronous orbit, but I guess I tend to group them all together). http://terra.nasa.gov/
Here’s one website (of many) that shows just how many planes are in the sky at any given time:
http://flightaware.com/analysis/map_day.rvt
Contrails are most visible on clear days. You’re most likely to notice them if you’re outside a lot. Everybody is outside more often when they weather turns nice, including violent criminals. News reporters come to expect (and dread) the increase in violent crime that hits when the weather turns nice… especially if it happens on a weekend. I think that explains any correlation between noticing chemtrails and their purported effects.
Air transportation does have an effect on our environment. Everything we do has some impact on the planet.
http://eoimages.gsfc.nasa.gov/images/imagerecords/4000/4435/contrails_southeast_lrg.gif
Contrail clouds can help trap heat and many studies have established the impact of air transportation on global warming.
If there really is a conspiracy at work here, it’s one that’s distracting us from issues we have the power to change. For example, pollution (mainly from automobiles) combined with the terrain of our valley give us some of the highest rates of childhood and adult asthma in the country. Poisoning and death from these chemicals occurs constantly, has a clear cause and is something we each have the power to change.
