Here in the USA, these are called Chemtrails. They are used to keep the normal rainy season from occuring in California to cause a drought and raise the cost of drinking water or the use of water for any of the reasons needed. Yesterday, 12/13/2011, I could see at least 40 streaks across the sky along the coast in S. CA. Looking out toward the Pacific Ocean I could see normal clouds that were being kept from coming ashore by those Chemtrail spraying. The weather forecast said it was going to rain Monday and Tuesday. It rained Monday, but it was kept from raining on Tuesday. Why? Same reason they use food to control people. Without rain people cannot grow their own foods when the SHTF, and that is very soon to happen.