A: Michael from Santa Cruz asked, "explain chemtrails, their composition and the reason for the spraying?"
Here's our Chief Meteorologist Norm Hoffmann.
I have answered a number of questions like this and may have answered your question, but I will try and answer it as best I can. I speak from a scientist point of view.
The Central Coast is one of the major corridors for jet aircraft routes, especially flying from north to south or south to north along the west coast. We have over 300 flights per day that fly over the Central Coast. Most of what you see is ice crystals that form on the exhaust of jet aircraft. Ice crystals form from the heat and air (exhaust) forced from the engines. They are called Contrails. They usually form when the temperature and the dew point are close together high in the atmosphere.
I watch the upper air sounding from Oakland and when the temperature and dew point are within 10 degrees Celsius (10 degrees or less in the upper atmosphere) we will start to see these contrails form. The jets are still there when the temperature and dew point at high levels (20,000 to 40,000 feet) are more than 10 degrees apart, but the contrails don't form because there is not enough moisture. Just as at the surface, fog forms when the temperature and dew point are close together and dew forms on your car or grass under similar conditions. The temperature and dew point have to be close together. When there are clouds the Temperature and Dew Point are usually with 3 to 5 degrees or less, but we generally don't see the contrails unless the clouds are thin.
When I was stationed in Japan during the Viet Nam War, we briefed air crews on when there would be contrail because that was the only way the North knew where the bombing runs were going to take place. I have flown in the cockpit of many commercial aircraft and all the pilots speak of contrails. They even form when there are clouds, most of the time we don't seem them. So it has been my experience they are just ice crystals.
You asked what are they spraying? I realize there are many people who think that some secret Government program s going on and I work in the media business, so I would be remiss in not giving you both sides of the issue. There are some that feel these trails are chemical trails, known as chemtrails. You can Google chemtrails and you will find a lot of information and passionate people who feel the Government is using commercial and military aircraft to spray chemicals in the upper atmosphere for a number of purposes. So I ask you to check for yourself, you can Google "Contrails" and read about those and Google "Chemtrails" and read about those as well and make up your own mind.
I hope that answers your question and thanks for asking.