Question

you can see your breath when you blow air out of your mouth in winters give reason

Answer 1

The reason is the water vapour in the air you exhale comes in contact with the cold air during winters so you can see it.

Answer 2

This scientific process is called condensation. When you exhale when it's cold outside, the water vapor in your breath condenses into lots of tiny droplets of liquid water and ice (solid water) that you can see in the air as a cloud, similar to fog.