The temperature dropped near me over the past week and today the clouds are noticeably lower than they were all summer.
In: 344
Clouds form when the air can’t hold water vapour anymore. This is measured by something called the “dew point”, the temperature the water *would* condense if it was that cold. If the actual temperature drops to the dew point, you get clouds. There are two ways for temperature to drop…it can get colder in general, or you can go up (temperature drops by about 3-9 C per km depending on how much water is in the air). For any particular weather condition, if the air is moist enough, there’s some altitude that will drop you from surface temperature to the dew point, and clouds bases will form at that altitude. You can figure out the dew point on cloudy days if you know the surface temperature and the cloud base height (“ceiling”) that way.
In the winter/fall it’s colder (on average), so the actual temperature and dew point get closer together, which means it takes less altitude rise to drop the temperture to the dew point…you don’t have to go up as far. So the cloud bases tend to be lower.
I’m not sure about the cloud bases being lower or higher but the tops will be lower in the winter time because of the height of the tropopause being lower with the colder air.
I’ve always assumed it’s because clouds appear where the temperature is low enough to allow condensation. As the atmosphere cools, that happens closer to the ground.
Latest Answers