It's HOT! It's COLD! It's WINDY! It's DRY! It's WET! It's OUR Weather! (appointed, inspections)

[DaveG99]

I think the heat has gotten to some of the people here and they are acting goofy.

[highcotton]

I just heard that the heat wave covers at least 10 states. Memphis is supposed to have a heat index today of 114 degrees, and 119 degrees in both St. Louis and Chicago.

You can see that any state near the Mississippi River, along with the Southeastern states, have high humidity levels that increases the heat index.

[highcotton]

Originally Posted by ladarron

Houston's heat index is 105.

Houston currently has a cloud cover, which is keeping the temperature down.

[highcotton]

Here's what makes you extremely uncomfortable - the high humidity (high dew point). As you can see, the entire southeastern states (and a great portion of the upper-mid U.S.) are dark green with high humidity...and any state close to the Mississippi River has high humidity. Take a look at New Orleans and the entire state of Florida - the dew point is well into the 70s. Later this afternoon the dew point will likely reach into the 80s, which is drenching wet.

[highcotton]

[ladarron]

Originally Posted by momofdfw

The heat index is supposed to be 108 in dallas today according to channel 4. High heat - High humidity. This is how it will be for the next 2 months.

The High pressure is bringing in the humdity from the gulf. The high pressure is causing the extreme heat around the USA.

[Ambassador]

Originally Posted by highcotton

Here's what makes you extremely uncomfortable - the high humidity (high dew point). As you can see, the entire southeastern states (and a great portion of the upper-mid U.S.) are dark green with high humidity...and any state close to the Mississippi River has high humidity. Take a look at New Orleans and the entire state of Florida - the dew point is well into the 70s. Later this afternoon the dew point will likely reach into the 80s, which is drenching wet.

A high dew point only means the air has a higher capacity for humid air. It is not a measure of how humid the air actually is. For that you need to find out what the relative humidity percentage is.

For example, hot air ( high dew point) has a greater capacity for holding moisture ( humidity) than colder air ( lower dew point). However, the relative humidity in Arizona can be 10% with the dew point at 80 ( hot air, dry air) while the relative humidity in Houston can be 45% with the dew point at 72 and it would feel MUCH more humid in Houston than Arizona.

Remember that the relative humidity measures how saturated the air is. Just because a parcel of air over your head has the capacity for holding more mositure doesn't mean it is completly full. A good rule of thumb is to look at the relationship between the dew point and temperature. The closer the two are to eachother the more saturated the air is ( higher relative humidity). Saturated colder air will not make you feel uncomfortable the way saturated hot air will. So a temperature/dewpoint relationship of 70/68 means you may see some fog or clody skies but feel very good outside.

[Canine*Castle]

Originally Posted by Ambassador

A high dew point only means the air has a higher capacity for humid air. It is not a measure of how humid the air actually is. For that you need to find out what the relative humidity percentage is.

For example, hot air ( high dew point) has a greater capacity for holding moisture ( humidity) than colder air ( lower dew point). However, the relative humidity in Arizona can be 10% with the dew point at 80 ( hot air, dry air) while the relative humidity in Houston can be 45% with the dew point at 72 and it would feel MUCH more humid in Houston than Arizona.

Remember that the relative humidity measures how saturated the air is. Just because a parcel of air over your head has the capacity for holding more mositure doesn't mean it is completly full. A good rule of thumb is to look at the relationship between the dew point and temperature. The closer the two are to eachother the more saturated the air is ( higher relative humidity). Saturated colder air will not make you feel uncomfortable the way saturated hot air will. So a temperature/dewpoint relationship of 70/68 means you may see some fog or clody skies but feel very good outside.

I found a dew point calculator and your example figures for AZ are not correct. I set the humidity at 10% and the highest the calculator would go was to 149 degrees with a dew point of 72. If there is a temperature of 110, the humidity would have to be 38% to have a dew point of 80. Hmm ... that sounds like some place in Texas.

With a temperature/dew point of 70/68, the humidity would be 93%. Of course, 70 degrees and humid with a high dew point isn't going to feel as bad as when the temperature is in the 90s but nevertheless, it will still be somewhat uncomfortable.

[DaveG99]

who cares how humid it is? When I go outside in 105 degree heat I am soaked with sweat after 10 minutes. When Im soaked with sweat the humidity might as well be 100% because Im wet.

[Sandstorm214]

Originally Posted by DaveG99

who cares how humid it is? When I go outside in 105 degree heat I am soaked with sweat after 10 minutes. When Im soaked with sweat the humidity might as well be 100% because Im wet.

You'd be surprised what a difference it makes. I've walked around outside in 100 degree heat in New Mexico without breaking a sweat. I'm drenched within five seconds of walking out the door in 100 degree heat in Arkansas or Louisiana.