The mixture of gasses that make up the Earth’s atmosphere. Excluding water vapour and dust, the main components of air are nitrogen, oxygen, argon, carbon dioxide, neon, helium, krypton, hydrogen, xenon and ozone.

Advection fog

A type of fog formed when warm, moist, stable air moves over a far cooler surface. It is most commonly found over cool sea areas in spring and summer, but does occasionally form over land in the winter, especially when the ground is frozen or covered by snow.