Coldest After Sunrise
It's true - our coldest temperature of the day is just AFTER sunrise. Laura from Southwest Portland sent me this email last week:
You mentioned something on this morning's newscast that reminded me of a question I've had for some time. It was about 6:20 and you said something along the lines of "we're about to hit the coolest temperature of the day"--as though we had not yet hit it.Here's my question--it has often seemed to me that the temperature dips just as the sun is coming up--it's colder after it starts to get light than beforehand. This seems counterintuitive--what is happening meteorologically that would cause the temps to dip? Does the rising of the sun create some sort of wind or something?
Laura, this is an excellent question. And here's the deal...
If we've got clear skies, then all night long, the heat from yesterday is escaping to outter space and temperatures keep cooling. It seems like that would change as soon as the sun comes up.
But when the sun comes up, it's so low on the horizon its rays are too weak and spread out to have an impact. So we keep cooling.
This time of year, it's about an hour after sunrise when the sun is high enough in the sky that its rays hit us more directly. And that makes them strong enough to finally start warming us up.
There you have it...
Bruce
