Answer:
Sorry I am writing in English but it would probably take me 2 hours to write in Hebrew Those clouds you see up there which called contrails are made up of condensed vapor called also condensation trails. They are generally produced by jets flying between 25000 to 40000 feet, but I have seen higher then these altitudes, and this is happening in a very moist air. If the relative humidity is low, the contrails may evaporate quickly, however in high relative humidity conditions, contrails may remain visible for several hours, and this indication of moisture content may point to other clouds and could also precipitations moving into the area within 1 or 2 days.