Staying Cool

Steve Scolnik, of CapitalWeather.com, was online Tuesday, July 10 at 2 p.m. ET to field your comments about the heat, and offer advice on how to stay safe and comfortable when the temperature soars.

A transcript follows.

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Steve Scolnik: Hello, everybody, and welcome to our chat about the heat.

I'm Steve Scolnik, the PM Update commentator at www.capitalweather.com.

As luck would have it, the humidity which increased overnight has "cooked" in the sun, and a weak low-pressure area moving through has helped set off some thunderstorms that should be cooling some of you off, at least temporarily. Some of our commenters at CapitalWeather.com have reported strong storms downtown and in the Capitol Hill area. Unfortunately, that will just increase the humidity in places where it rains and make it even more muggy until some real relief can arrive in a couple of days.

If you have some favorite ways to beat the heat, please share them or ask some heat/humidity related questions.

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Washington, D.C.: Is there such a thing as a "humidity scale"? The humidity in the Washington area, unless it has JUST rained, does not feel like the humidity in Florida or the Caribbean or Vietnam. It's a much drier-feeling humidity. Which is why I wince when forecasters here call for "hot, humid, muggy" weather. This is not humid or muggy! It's just plain hot, with lots of haze, which is typical of the region. For hot, humid or muggy, try Miami, where mildew grows everywhere, even on sidewalks, and you sweat 24/7!

Steve Scolnik: That's a good question. There are several different ways of measuring humidity, both relative and absolute. The "relative" humidity (it was 38% at National Airport at 1:00) compares the amount of moisture now in the air to the maximum amount which could be held at that temperature. A more consistent way to measure humidity is the dew point, which is the temperature at which the moisture now in the air would condense. The dew point readings the last couple of days have actually been fairly comfortable here, but they increased last night and are now mostly in the 70s, which is a lot muggier and much more typical of what you would find in the tropics.

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Downtown, D.C.: With these afternoon thunderstorms today, it looks to have cooled off a bit. Will it stay cooler or do you expect it to warm back up again later this afternoon/evening.

Steve Scolnik: Since the storms are developing early in the PM, the sun will pop back out and push the temp back up along with more humidity where it's rained.

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Annandale, Va.: Could you please settle this debate: When is the hottest part of the day in the DC Metro area?

Steve Scolnik: That really depends a lot on the season. In the summer, the sun has a lot longer to build up the heat, and so the max occurs at a later time. Yesterday, for example, the high at National wasn't until 4:20, which would be more like sunset time in the winter. There's also daylight savings vs. standard time, of course.

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Egg Harbor Township, NJ: I've always heard that the sun's rays are most intense between 10 a.m. and 2 p.m., is this true? If so, how much more intense is the sun during those hours and how how much more dangerous in terms of sunburn, sun poisoning, and, long-term, skin cancer?

Steve Scolnik: The intensity of the sun's rays depends a lot on the angle. That's why the winter is colder than the summer in the Northern Hemisphere--the sun is at a lower angle in the winter because of the tilt of the earth's axis of about 23 degrees. The angle, of course, also changes during the day, so it's much more intense in the middle of the day. We occasionally publish a chart of sun angle at www.capitalweather.com. I'll try to add the exact link to the transcript if I can.

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Washington, DC: Why is it that almost no one in my town seems to have awnings? I've read that awnings could reduce your cooling needs in the house by 25 percent -- and if you set them at the right angle, they can stay up all winter and still let in the sun to assist with heating your house, since during the winter the sun is at a lower position in the sky. If not awnings, what about some sort of blinds that operate on the outside of the window?

If you go to places like southern Italy, you'll tend to see less use of air conditioning but greater use of awnings on residences. Is there a reason that they've never caught on here?

Steve Scolnik: That's a great point about awnings. My family had them on our old house in Maine. I think they probably just went out of style with the popularity of AC. As the last question indicated, sun angle is a very important factor in heating. The south-facing French doors on my family room act like a sundial during the year. In the winter, the sun's rays come far into the room and help heat it, but the much higher sun angle in the summer keeps most of the heat out. Adding awnings would help balance the heat even more.

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DuPont Circle: Hi Steve,

For someone that relies on jogging 5-6 miles a few times a week for exercise, what is your recommendation for said activity during this heatwave? Could jogging in this kind of muggy heat actually make me LESS fit?

Steve Scolnik: There is some great material about the effect of heat on sports at www.zunis.org. (That's where I got the heat index equation for the chart in yesterday's PM Update at www.capitalweather.com .)

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Dew Point, D.C.: In my experience, dew point seems to be the ultimate measure (compared to temperature and humidity) of how bad it is outside. For example, running when the dew point is in the 70s is not pleasant. Can you explain why high dew points make us feel lousy?

Steve Scolnik: The effect of the combination of heat and humidity on the body is a little complicated, but basically the closer the dew point gets to body temperature, the more difficult it is for sweating to cool you off.

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Reston, Va.: Any tips for those of us who have to walk outside from one place to another during the day? Lots of water, shoes with some ventilation, etc.?

Steve Scolnik: If you don't mind the dorkiness factor (and perhaps cost!), the WaPo had some interesting suggestions last August.

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Silver Spring, Md.: Hi there. I know that in conditions such as this the "infirm" are cautioned to stay indoors as much as possible. But what about pets? I like to walk (definitely walk, no running) my dog daily, but don't want to do more harm than good. Thanks!

Steve Scolnik: Pets are affected by heat much like people are. Don't forget to let them have plenty of water, and be careful especially not to leave them in a closed car, which can heat up to about 140 degrees in the sun very quickly.

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Central, D.C.: Where the heck are you? We've been getting almost constant thunderstorms for the past two hours, and the temperature has dropped about 15 degrees. (Just looked out the window -- yup, thunder and heavy rain.)

Steve Scolnik: These storms have been very localized, although radar shows them recently stretching from about Bethesda downriver through Alexandria. In this part of MoCo, we've only had some clouds and the rumble of thunder, but no rain.

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Capitol Hill: What's up with these storms? Unusual/atypical type of T-storms, right?

Steve Scolnik: These storms are earlier in the afternoon and more scattered than what my Dad the civil servant used to call the "government showers" arriving in time to get the commuters wet at 4:30.

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sailing on the Potomac: No question, just wanted to extend my thanks for your work on capitalweather.com; what a great site! Weather info is crucial to sailors, and I make capitalweather.com one of my must-check sites before going out on the water.

Steve Scolnik: Thanks for the compliment! Wind, especially speed, is one of the trickiest elements to forecast, since it tends to vary a lot during the day.

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Hot Hot Washington: Steve - Washington has a harried pace that does not go well with very hot weather. Don't forget to remind chatters to work on their sauntering skills.

saunter:

to walk about in an idle or leisurely manner ; STROLL

Steve Scolnik: An excellent suggestion! I think a little more sauntering would be beneficial in any kind of weather.

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Falls Church, Va.: I go running every day at lunchtime on the Mall for 3 or 4 miles, and only stay in if it is a "Code Red" day. Today, before the storm, it must have been 90 degrees. I got a little light-headed toward the end, but nothing too bad. I go out mostly because my office has no windows, and the prospect of using our windowless gym for 45 minutes is not appealing. Am I an idiot for running in the heat?

Steve Scolnik: Mid day is probably the worst time to run because of the intensity of the sun angle we mentioned earlier. Check out the link to www.zunis.org for much more sports information.

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re: "government showers": My friends and I call them the Five O'Clockalypse....

Steve Scolnik: Excellent!

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Boston: I have a window unit air con and everyone says to make sure it has a good "seal" to it but they don't say much else. Is this seal to be on the inside or outside? What materials are on offer to do so? What method is the best for those of us who are DIY challenged? I don't care what the window ends up looking like -- I just want the cool air to stay inside! Any help gratefully received.

Steve Scolnik: Being DIY challenged myself, I would have to refer that question to Danny Lipford at The Weather Channel. I would think that any kind of caulking would help block the air leakage.

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Boston: I've horrified people when I describe sleeping with a cool damp towel to beat the heat, because they regard it as a health risk: getting pneumonia from this exposure. It works, and if the temperature dropped, I'd certainly wake up. Reassure them, please.

Steve Scolnik: That sounds like the "desert method" suggested by Real Simple magazine. Check out the rest here.

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Washington, D.C.: So, in layman's terms, what causes these very localized downpours/thunderstorms? It's hot all over the area, but while it's raining outside my office downtown, my wife is baking in the sun three miles away.

Steve Scolnik: We've got all the right ingredients: humidity, heating, and a little boost from some upper-air instability, but exactly where the storms will pop at any given time is kind of random. It's sort of like trying to predict which kernels of popcorn are going to pop first.

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Cola, S.C.: Unfortunately I don't tolerate the heat very well (I start to sweat before anyone and don't cool down easily -- even when just wearing a little sundress!) and I live in a very hot area. Is it possible to make my body more acclimated to the heat? I just went to an outdoor wedding and was miserable! I dread any non-casual outdoor events in the summer.

Steve Scolnik: Temperatures do seem to affect people very differently. Who controls the thermostat is just as big an issue as who controls the remote in many households. (I think there was an article about this in the Style section a couple of years ago.) The Heat Index is supposed to tell what the effect of a certain temperature and humidity will be on the body, but it's just an estimate based on some theory and the average of some measurements.

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Steve Scolnik: Thanks everyone for an interesting discussion. To continue discussing the weather 24x7, please join us at CapitalWeather.com and submit your thoughts via the "Comments" link.

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