But it's a dry heat....

"Dan Luke" wrote in message
...

"Matt Barrow" wrote:
The same day it hit 104 in Chicago and ...the humidity was 90+/-
percent.

Baloney.

Look at a psychometric chart:

http://www.rfcafe.com/references/gen...tric_chart.htm


Ever hear of "Heat Index"?

Yes.

What's that got to do with your made-up statement that the temperature was
104 F. and the humidity was 90%?

How was that made up? Check the weather records from June, 1990. Do a google
search on heat related deaths in Chicago.

Did you attempt to understand the chart?


Yes, and I understand your point, thank you. I assume your point is that one
would perspire more at 120 than at 104. If so, that wasn't my point.

One thing...When the desert gets how it still cools substantially during the
evening and night. When humid air gets hot (like the 104-105 that Chicago
had, the heat effect holds. I suspect that a couple days of this is what
kills so many and did back in 1990.

"Matt Barrow" wrote:

Yes.

What's that got to do with your made-up statement that the temperature was
104 F. and the humidity was 90%?

How was that made up? Check the weather records from June, 1990. Do a
google
search on heat related deaths in Chicago.

I meant the part about 90% RH. If you look, you'll see that's off the chart
at 104 deg. F.

Did you attempt to understand the chart?


Yes, and I understand your point, thank you. I assume your point is that
one
would perspire more at 120 than at 104. If so, that wasn't my point.

No, my point is that 90% RH at 104 deg. F. is not a set of conditions one
will find in the surface atmosphere. People often assume that the humidity
is much higher than it actually is when the weather is warm. At 104 deg. F.,
50% RH would be awfully uncomfortable; 90% RH would be, if not impossible,
damned near it.

Relative humidity is the humidity you feel. Given constant absolute humidity
(no front, rainstorm), the highest relative humidity occurs at the coolest
part of the day, usually around dawn.

One thing...When the desert gets how it still cools substantially during
the
evening and night. When humid air gets hot (like the 104-105 that Chicago
had, the heat effect holds. I suspect that a couple days of this is what
kills so many and did back in 1990.

The heat holds because of the high dewpoint. The dewpoint acts as a low
limit to temperature fall because of the heat of condensation--as atmospheric
water condenses it gives up heat and warms the air. The higher the dewpoint,
the higher the overnight low. Cloud cover can also affect this by slowing
radiaton cooling.
--
Dan
C-172RG at BFM

"Dan Luke" wrote in message
...


No, my point is that 90% RH at 104 deg. F. is not a set of conditions one
will find in the surface atmosphere. People often assume that the
humidity
is much higher than it actually is when the weather is warm.

Which is probably how the folks in Chicago were describing it to us. Having
been there in the summer just a few times, I do know you just get wringing
wet just standing outside.

On the other end, I also recall a few episodes of shoveling snow, here in
Colorado, wearing only a light jacket. And, no, it wasn't that the exercise
was keeping me warm. We get nice fluffy powder, the easterners/northerners
get slush.

At 104 deg. F.,
50% RH would be awfully uncomfortable; 90% RH would be, if not impossible,
damned near it.

Sometimes, the "near impossible" happens :~)

My in-laws live in Scottsdale, and I've been there a few times during the
summer (dragged kicking and screaming). It's so amazing to be in such heat
and your shirt is bone dry, contrasted with the wringing wet mentioned
earlier, in the high 80's, low-mid 90's.


Matt
---------------------
Matthew W. Barrow
Site-Fill Homes, LLC.
Montrose, CO