Over 100, and a dewpoint over 70?

[LeeJet]

How does the Persian Gulf manage to have over 100 degree temps, while at the same time having extreme, tropical, humidity levels? I mean, why doesn't Miami get 100 degree weather while Dubai does?

[AussieMark]

the Persian Gulf have humidity?

I thought it being around desert it would be dry heat

learn something every day

[Aslkahuna]

The Persian Gulf sees the highest average dewpoints in the World and they manage to do so the same way Yuma has been able to come in with a 113/77 reading. Miami doesn't get to 100 usually because the airmass is unstable and uncapped consequently they get a lot of afternoon clouds. In the humid deserts like the Sonoran and around the Persian Gulf there is usually strong subsidence which caps everything. Also, Sea Breeze mechanisms are not as strongly developed in the latitudes of Yuma and Persian Gulf as they are in the lower latitudes of Florida. I'm not sure about the Persian Gulf, but Yuma does get surges of low level moisture in form the Sea of Cortés but because of the high sea surface temperatures all they do is maybe lower the temperatures from the 115-120 levels to a much more humid 100-110F.

Steve

[LeeJet]

The Persian Gulf sees the highest average dewpoints in the World and they manage to do so the same way Yuma has been able to come in with a 113/77 reading. Miami doesn't get to 100 usually because the airmass is unstable and uncapped consequently they get a lot of afternoon clouds. In the humid deserts like the Sonoran and around the Persian Gulf there is usually strong subsidence which caps everything. Also, Sea Breeze mechanisms are not as strongly developed in the latitudes of Yuma and Persian Gulf as they are in the lower latitudes of Florida. I'm not sure about the Persian Gulf, but Yuma does get surges of low level moisture in form the Sea of Cortés but because of the high sea surface temperatures all they do is maybe lower the temperatures from the 115-120 levels to a much more humid 100-110F.

Steve

Yuma's dewpoint is the 50's, while Dubai is in the lower 80s, and upper 70's. Right now, at night, the temperature is 99, with a dewpoint of 75, making is feel like 112. Clearly Yuma is not as humid as the Persian Gulf!

So basically the Persian Gulf manages to get that hot because of a strong cap? What do you mean by "cap"? Also, it doesn't explain why their dewpoints are higher than even Florida's.

Look at this:

http://www.weather.com/outlook/travel/b ... v_business

The dewpoint in Doha is 86!!!!

[Aslkahuna]

Yuma's dewpoint is in the 50's right now but watch the trends and you will see times when it and the dewpoints in the Imperial Valley and up to Needles will suddenly jump into the 70's to low 80's. In fact, the dewpoint at Phoenix hit 81F last month. Miami doesn't see dewpoints that high because the air is usually well mixed out by convection. That's where the cap or atmospheric lid caused by subsidence works into the mix. The subsidence causes a warming of the upper atmosphere to the point where convection is capped and is no long able to proceed which prevents the lower levels of the atmosphere from mixing out. This allows moisture levels to build up in the lower level since the surrounding waters are very warm (above 32C). At the level of the subsidence inversion and above the air is very dry and if the air could be mixed out the dewpoints would be much lower there but it can't be. The same process though with cold water works to produce the Chilly fog in NoCA during the Summer where the cold air is topped by warm dry air.

Steve

[Hybridstorm_November2001]

The Persian Gulf sees the highest average dewpoints in the World and they manage to do so the same way Yuma has been able to come in with a 113/77 reading.
Steve

You really do learn something new everyday. I was not aware of this, thanks for the info.

[LeeJet]

Yuma's dewpoint is in the 50's right now but watch the trends and you will see times when it and the dewpoints in the Imperial Valley and up to Needles will suddenly jump into the 70's to low 80's. In fact, the dewpoint at Phoenix hit 81F last month. Miami doesn't see dewpoints that high because the air is usually well mixed out by convection. That's where the cap or atmospheric lid caused by subsidence works into the mix. The subsidence causes a warming of the upper atmosphere to the point where convection is capped and is no long able to proceed which prevents the lower levels of the atmosphere from mixing out. This allows moisture levels to build up in the lower level since the surrounding waters are very warm (above 32C). At the level of the subsidence inversion and above the air is very dry and if the air could be mixed out the dewpoints would be much lower there but it can't be. The same process though with cold water works to produce the Chilly fog in NoCA during the Summer where the cold air is topped by warm dry air.

Steve

Thank you for your concise response! I don't quite understand all of the technical stuff, but I gather that basically Yuma's/Persian Gulf's atmosphere is more stable, and that moisture cannot escape like in Miami, hence in the higher dewpoints. Tell me, is there is a difference, between a dewpoint in the the 70's and then in the 80's? Does one feel much more moisture?

Thanks!

[JonathanBelles]

miami is surrounded by warm water that controls the temperature to 90 degrees

[LeeJet]

miami is surrounded by warm water that controls the temperature to 90 degrees

Qatar is also surrounded by warm water, and yet they get soaring tenps over 110 with high humidity.

[Jim Cantore]

Heck, last week I had 104 with a 76 dewpoint, down right miserable.

[Aslkahuna]

You better believe you can feel the difference between a dewpoint in the 70's and one in the 80's. BTW might want to check the cornfields of Iowa on occasion-dewpoints in the 80's occur there quite regularly during hot weather.

Steve

[Jim Cantore]

You better believe you can feel the difference between a dewpoint in the 70's and one in the 80's. BTW might want to check the cornfields of Iowa on occasion-dewpoints in the 80's occur there quite regularly during hot weather.

Steve

I've never felt a dew point in the 80s and I never want to. 76 was unbearable enough

[bob rulz]

I don't like feeling humid heat at all. We rarely get dewpoints above the low 60s here (and usually it only gets to that point when it's raining).

[kevin]

Gah humidity bah

[senorpepr]

You better believe you can feel the difference between a dewpoint in the 70's and one in the 80's. BTW might want to check the cornfields of Iowa on occasion-dewpoints in the 80's occur there quite regularly during hot weather.

Steve

Yes, Steve...

People tend to forget that the Great Plains can get really nasty.

A few times over the past few years Nebraska and Iowa have seen temperatures above 100 with dewpoints at or above 80. ...and with nothing to do but play in the cornfields... it get's sickening.

FWIW, places like the Philippines see dewpoints in the 80s frequently. While the temperatures aren't as high (in the low 90s), it still feels awfully nasty, espeically if there are no air conditioners in sight.

-Mike

[Aslkahuna]

Highest dews I saw at Clark AB were in the 79F range but the higher dewpoints would occur on the smaller islands and near the water. The worst time of day over there would be in the late morning/early afternoon before the seabreeze kicked in (and in the Tropics, the sea breeze not only goes further in land but is quite healthy speed wise) and in the evening before things cooled off much unless we got a an early evening boomer. That's when you lit the mosquito coils and turned on the fans to keep the skeeters from landing on you. Once acclimated, you got rather used to it and I spent a number of years there without A/C. For us, the worst time would be just before the onset of the Summer monsoon when we had 100F temperatures or after the end of an extended period of rain when everything was soggy and it got hot.

Steve

[wxmann_91]

You better believe you can feel the difference between a dewpoint in the 70's and one in the 80's. BTW might want to check the cornfields of Iowa on occasion-dewpoints in the 80's occur there quite regularly during hot weather.

Steve

Oh yeah, I remember during the St. Louis derecho on July 19 of this year, Webster City, IA had a dewpoint of 86 with temps in the 90's. Of course, the MDT risk in IA on that day didn't verify since the cap never broke.

[senorpepr]

Highest dews I saw at Clark AB were in the 79F range but the higher dewpoints would occur on the smaller islands and near the water. The worst time of day over there would be in the late morning/early afternoon before the seabreeze kicked in (and in the Tropics, the sea breeze not only goes further in land but is quite healthy speed wise) and in the evening before things cooled off much unless we got a an early evening boomer. That's when you lit the mosquito coils and turned on the fans to keep the skeeters from landing on you. Once acclimated, you got rather used to it and I spent a number of years there without A/C. For us, the worst time would be just before the onset of the Summer monsoon when we had 100F temperatures or after the end of an extended period of rain when everything was soggy and it got hot.

Steve

I haven't spent much time in Luzon, my Filipino experience is in the Visayas (Negros Oriental) where my fianceé lives. The highest I've seen their dewpoint was near 83. Of course, my time in the Philippines is limited altogether, so I've never become acclimated.

[Aslkahuna]

I spent time on Mactan close to Cebu but that was during the NE Monsoon which is generally cooler and with somewhat lower dewpoints. However, the Visayas would definitely have higher Summer dewpoints because of the land/water mix.

Steve