Answer :
this is because of a phenomenon called latent heat of condensation,
Latent heat is the total amount of energy required for particles to change from one state to another( in this case water molecules to liquid state) there is always moisture present in air including our breathe so when we breathe and this comes in contact with the plane it absorbs energy from the surroundings and also from our warm breathe and the water molecules change there state.
Latent heat is the total amount of energy required for particles to change from one state to another( in this case water molecules to liquid state) there is always moisture present in air including our breathe so when we breathe and this comes in contact with the plane it absorbs energy from the surroundings and also from our warm breathe and the water molecules change there state.