CHARLOTTE, NC (WBTV) - When you look at the weather map and see the big blue "H," that's typically a good thing. It means high pressure is over us. Unfortunately, this week, it's a double-edged sword. The very same system bringing us nice weather is keeping the much-needed rain away.
Here's how it works. High pressure, in a nutshell, means a big area of sinking air. Yep, that's it! (A low pressure system is just the opposite – rising air.)
How does that affect us?
To have clouds, which you obviously need for rain, you need two main ingredients - rising air and water vapor. If you have lots of sinking air, 50% of your cloud recipe is off.
Sure, you can still have clouds but it's like any recipe. You don't get a very tasty cake if you leave out the sugar. In this case, you aren't as likely to get rain producing clouds with sinking air.
Here are some things that aren't helping our drought situation right now.
- High pressure’s sinking air, is tampering with the above rain recipe.
- High pressure also has counterclockwise circulation around it. That means our wind is out of the north. There’s no major body of water to our north so water vapor is in short supply. (Although, not a bad thing if you’re enjoying the low humidity levels.)
- For every dry day, we aren’t just missing out on rain, we’re losing water. Water is evaporating from the ground and from bodies of water. Plus the low humidity levels just enhance evaporation rates.