Q: Why is it Colder When Sun Rises? - Central Coast News KION/KCBA

Q: Why is it Colder When Sun Rises?

A: Miguel from Salinas asked us, "in the early morning it's usually a certain temperature, but when the sun starts to rise it get colder, why?"

Here is Chief Meteorologist Norm Hoffmann:

In most cases the answer is pretty straight forward. Without a lot of wind, or cold air advection (cold air replacing warmer air), the minimum temperatures occurs usually within 30 minutes to 90 minutes after sunrise (depending on the weather conditions). This is because as the sun comes up it might feel warm initially, but it still is going through a lot more of the earths atmosphere (at a low angle) then when it is high in the sky say at noon. Therefore much of its energy is scattered and because of the low angle it does not have much impact on the atmospheric temperature at the surface. So it takes a little while before it is high enough before it can have an impact. The second reason is that in most cases at night the coldest air is near or at the surface and that air, being more dense and colder, takes a longer to warm up.

So once the sun is higher in the sky it begins to warm the air above the ground (and the ground surface) and the temperature begins to rise. This is why the minimum temperature usually occurs within 30 to 90 minutes after sunrise. It is even later if you live in a valley and there is little wind and the sunshine takes more time to hit the bottom of the valley.

The minimum temperature at Salinas this morning occurred at 7:30 am, about 30 minutes after sunrise. The minimum temperature at Hollister occurred between 7:10 and 7:30 this morning. Sunrise was at 7:04.