When conditions line up
Morning fog
Valleys and rivers filled with cloud at first light.
When and where to look
Dawn after clear, still nights, most often in autumn. It usually lifts within a few hours of sunrise as the sun warms the ground.
Why it happens
After a clear, calm night the ground cools and chills the air just above it until the moisture condenses into a cloud at ground level. Cold air drains downhill, so fog gathers in valleys, over rivers and in low fields.
How to catch one
- Head up a little: from a hill you can see fog lying in the valley below.
- Look for the sun breaking through; the beams are best in the first hour.
- Listen too. Fog softens and carries sound.
Nature notifications
Wildlife, seasonal changes, weather and sky events near you.