Tucson experiences the first 100-degree day Thursday | Local news

May 22, 2006

Tucson’s temperature hit 100 degrees Fahrenheit for the first time on Sunday afternoon, according to local meteorologist Jimmy Stewart.

The National Weather Service says temperatures will drop to 91 and 93 degrees on Monday and Tuesday, but will return to the century mark by the middle of the week.

Here are the answers to some burning questions about heat pulled from the Star 2005 archives:

Q: Should you leave your air conditioning on when you leave home for work?

A: Yes, but increase the thermostat setting 4 or 5 degrees above the normal setting, said Leroy Johnson, general manager of Cummings Plumbing, Cooling and Heating in Tucson.

When you turn it off, you’ll have to cool every surface and item in your house before the air feels cool again, which means it “runs for hours trying to draw heat out of the house,” Johnson said.

Johnson’s advice is backed by the Air-Conditioning and Refrigeration Institute, which represents 90 percent of air conditioning manufacturers in North America.

The website recommends turning the thermostat to around 82 degrees if you are going to be away for more than four hours. Those of you who can’t remember turning off your coffee maker before going to work should invest in a programmable thermostat.

For more information, please visit www.ari.org, the institute’s website.

Q: Why is dry heat better than damp heat?

A: A bone-dry 110 may feel like an oven, but it’s an environment that humans can at least function in. However, if you add a little moisture to the air, 95 degrees becomes a miserable endurance test. Why?

Wet air just feels warmer.

“As the relative humidity increases, the air usually seems warmer than it actually is because the body is less able to cool itself,” said Jeff Davis, a meteorologist with the National Weather Service. “The apparent temperature is much higher when it is damp than when it is dry.”

Meteorologists measure the influence of humidity on temperature by means of the heat index or “feeling temperature”. The heat index is essentially the opposite of wind chill.

Since people cool off by sweating in the heat, moist air can have more negative effects than dry air.

“When you sweat, sweat is essentially an evaporative cooling process and you’re basically cooling your body,” said Davis. “When there is more water vapor in the air, your body is not sweating as effectively as it should.”

Q: Should you put your sweaters away by December?

A: No actually.

On really hot days, recording a movie can be a relaxing and fun way to escape the heat.

But going from the heat of a 106-degree day to the air-conditioned cold of a theater can be a shock to the system.

What’s the healthiest way to deal with it? Wear a sweater.

Going without a sweater is safe, said Harvey Meislin, an emergency doctor at University Medical Center.

However, wearing one can help your body adjust to extreme climates quickly.


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