Why does the streak of smoke from small airplanes stay in the sky for a long time?
They end up becoming the 'seeds' of clouds.  That is, water in the air condenses around them, & once the process starts, those condensation  trails sometimes form into clouds up to 500 miles long.\n\nI read about it in, I believe, Popular Science a couple years ago.  There was also a fascinating article about a study that took place during the 3 days in 9/01 when all planes in the U.S. were grounded:  due apparently to the reduced cloud cover, temps everywhere were a couple degrees higher those days!
check this you will find the right answer\n\nhttp://answers.yahoo.com/question/index;_ylt=AgkOxzlGWY6TlgCBqQoOOl.izaIX?qid=1006011902162\n\nPlz dont reapeat questions.\nThis question is also seen by me earlier.\n\nDon't feel bad. I just wanna to say If the peoples like you (who ask good questions generally) start repeating the questions than how it can be interesting to answer same question again and again.