Wednesday, June 11, 2008

6/11 - 3pm - Not Too Bad Today!

Temperatures right now are holding in the upper 80's and dew points are in the mid 40's. That's not so bad is it? 90's are expected tomorrow with 80's and some rain for Friday and Saturday. It won't feel too hot since the humidity will be lower than last week.

A question was raised about the relationship between humidity and dew points and I'd like to clear that up since we're heading into the time when this is pretty crucial for heat index. The dew point is the temperature where the air is completely saturated. For instance... If the temperature is 90 degrees and the dew point is 90 degrees, then the air is completely saturated... no more water can be added or else the water in the air will condense (that's why its the DEW point, the temperature where dew forms on the grass). This also means that the humidity is 100%, which does make the air feel heavy and sweat on your body cannot evaporate, thus making it feel hotter than it really is. The higher the humidity, the less sweat can evaporate from your skin into the surrounding air. If the temperature is 100 degrees, but the dew point is 80, then the humidity is at 80%. To give you an idea how dew point feels, 65-69 feels oppressive, but anything over 70 is just unbearable.

So... Humidity is just a ratio of temperature and dew point. Humidity influences heat index (how it really feels outside), and you can find charts relating heat index and humidity on the web. That's my weather sermon for today...

I'll be at the Bonnaroo Music Festival in Manchester, TN this weekend, so this will be my last post until Monday or Tuesday. Stay cool!

2 comments:

Anonymous said...

Put on your thinking caps...

Q: What happens to the human body if the dew point were to reach 98.6 degrees?

A: You would condense water in your lungs and drown to death.

Seriously.

That concludes today's class.

MTWC said...

Highest dew point ever recorded was 95ยบ in Saudi Arabia. That makes Mississippi look like a desert!
-Clay in Nashville