Autumn feature explainer: It's fog season!

As colder and calmer weather becomes more frequent, we're more likely to see some more fog.

Autumn and winter is the perfect time for fog to develop, especially in periods of high-pressure dominated weather, with weaker winds allowing dense, stubborn fog to settle, even for days at a time.

This is because in the cooler months, under clear skies at night, heat from the ground can quickly escape allowing for the temperature to drop below the dew point.

There are several types of fog that form in different ways, including valley fog, radiation fog, advection fog, and sea fog, often a result of advection fog.

Because of the many factors involved, forecasting the arrival and exact location of fog is actually quite tricky. If just one aspect of the development is out of sync, fog is unlikely to form.

Cloud cover, wind speeds, temperature, moisture levels, and daylight hours all play a role.

A different type of fog can also occur in sub-zero temperatures, this is called freezing fog and will become a more likely occurrence in the depths of winter, rather than autumn.

The water droplets from the drizzle in the fog become supercooled, still remaining in liquid form in the sub-zero air.

They then freeze instantly upon coming into contact with an object or surface, creating what is called rime. This is a layer of tiny ice crystals, creating wintery landscapes.

To learn more about exactly how and why fog forms, check out our Weather Explained video below: