Weather

We can see sometimes  contrail.
 It's called"Hikokigumo" in japanese.
By the way,how is contrail made?
Contrail is made by airplanes.
It is said that humans see contrail about 60 years ago first.
Airplanes fly very high atitude and its temperrature is very low.
So, steams that airplane makes become ice .
Seen from ground,they look like cloud.
Also,when airplanes fhy very high altitude ,coils are caused behind of the airplane.
This coils may make temperrature around them low very quickly,and clouds are caused.
The combinations of these factors make contrail  finaly.