Many people in New Mexico and Coastal Texas have been reporting trails at a altitude of between 12,000 and 15,000 feet, far below the normal 30,000 feet and -35F need to produce a normal contrail. It has been noticed with relating the Winds and Temperature Aloft that the spraying will usually be more intense if the wind speed is under 25 miles per hour. These lower altitude trails are chemtrails, the spraying of a chemical/chemicals into the atmosphere for possible weather modification.
First you have to know your ground elevation to work into the equation of chemtrail altitude above sea level. Then you will need to go to a airport to observe large aircraft taking off and landing. Position yourself 2 miles/kilometers away from the aircraft that are landing and taking off. Now use a ruler at a arms length away to get a reference size of the aircraft to the ruler. Next move your position to 5 miles/kilometers away from the aircraft and reference the size of the aircraft to the ruler. Move to 7 miles/kilometers away and repeat with ruler. You now will have a good idea of the size of a aircraft to different altitudes when they are directly overhead. If the aircraft and trails you are observing are to the N,S,E,or W of your ground position, you will need to adjust to the added distance of the aircraft position away from your ground location to roughly determine the altitude above sea level.
Here is a URL to find locations near you for information on the wind speed and temperature at different altitudes:
Winds and Temperatures Aloft (FD)
Produced by the Aviation Weather Center
Also you can find more information for aviation weather at:
Official Forecast Products at:
Winds and Temp Aloft for South East US
TLH = Tallahassee, Florida
Altitude in feet along the top. Under each altitude in feet are wind speed and air temp. At 18,000 feet is a wind speed of 30.28 miles per hour and a air temperature of -12F. 30,000 feet and above the air temps are always minus. 30,000 feet at this location will be where a normal jet aircraft contrail will form, the temperature is at -40F.
Hope this helps everyone with determining what is or is not a normal contrail!