How does fog form?

The sight of fog is not rare across the UK and Ireland, but do you know exactly what it is and why it appears?

There are actually five different types of fog that form in slightly unique ways. Cloud cover, wind speeds, temperature, moisture levels, and daylight hours all play a role.

Despite fog being somewhat regular during cooler months, it is harder to forecast than you might think.

This is because if just one of the many factors that are needed for development are slightly out of sync, the fog does not arrive. Meaning even small miscalculations in a forecast can miss or inaccurately predict a foggy day.

In addition to regular fog, we also see freezing fog in the UK and Ireland. This occurs when fog develops in below-freezing temperatures.

Freezing fog sees moisture supercooled in the air, when this moisture makes contact with a surface it instantly freezes and creates what is called rime.

This is a layer of tiny ice crystals, creating wintery landscapes.