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As Summer Sizzles, So Do Home Runs and Crime

Dan Stillman @ 11:35 PM

As tired as I am of the heat, haze and humidity this summer, in my book it beats the gloom and doom that cast a shadow over the area yesterday. Overcast skies and in some places a steady rain kept yesterday's temperature to a high of 76 at National and Dulles, and 75 at BWI. The high of 76 at National was the lowest high recorded at the airport since June 20 when the temperature topped out at only 75.

While I think we'll start off with a lot of leftover clouds this morning, and there could be a lingering shower or two, I expect the sun to break through as the day goes on. Temperatures will rebound from yesterday -- how could they not? -- for a high in the mid-to-upper 80s.

Temps are back into the low 90s tomorrow and low-to-mid-90s for Friday and the weekend. Friday afternoon and evening, Saturday afternoon and evening, and throughout the day on Sunday present the best chances for rain as it stands now.

Baseball Weather

Photograph by

Baseball is back in Washington, which means it's time to clear up some confusion regarding the effect humidity has on home runs. I've come across some misleading comments about this topic on local sports radio and online baseball chats. The source of confusion seems to lie in the myth that humid air is just dry air with water molecules added to it. Using that logic, one would conclude that humid air has more molecules than dry air, and is therefore more dense. The higher density, the thinking goes, slows the flight of a baseball, thus making it harder to hit a home run.

The truth is dry air and humid air have the same number of molecules. It turns out the increased number of water molecules in humid air comes at the expense of nitrogen and oxygen molecules. In other words, as water molecules come into the air, nitrogen and oxygen molecules leave. The result is that humid air is actually less dense than dry air because water molecules (H2O) have a lower molecular weight than both nitrogen (N2) and Oxygen (O2) molecules. Thus, humid air would be considered more conducive to home run balls than dry air.

However, other environmental factors tend to have a greater effect than humidity on the flight of a baseball. Air pressure, temperature and wind are the main culprits. The impact of wind should be quite obvious, but what about pressure and temperature? As pressure decreases, air expands and the air molecules spread out, therefore making the air less dense. This is why baseballs carry so well at Coors Field in Denver, where the high elevation means lower air pressure. Meanwhile, an increase in temperature causes molecules to bounce around more actively. This also expands the air and lowers its density.

For the Nats, all the heat, humidity and expanding air in the world may not be enough to help them out with home runs. They have the fewest of any team in the major leagues, even after last night's season-high four-homer performance. And as for Rafael Palmeiro, I have a feeling weather wasn't the only factor contributing to his hitting prowess.

For more on this topic, check out the Exploratorium's Science of Baseball.

Irene Still Finding Her Way

Although Irene was a rather weak-looking tropical depression way out in the Atlantic as of last night, she is expected to strengthen as she slowly heads in the direction of the United States. We'll have to keep our eye on this one. It's certainly possible that Irene could reach hurricane status over the weekend and threaten the U.S. mainland next week.

Summertime is Crime Time

DCist calls attention to the annual summer spike in Washington-area crime, now in full swing. Is it, as the DCist post suggests, the nicer weather that brings out the criminals? I guess summertime does indeed provide a more comfortable working environment for the criminal element than the dead of winter. But according to the Washington Post, a more likely reason for the rise in crime is the increased number of people -- potential victims, that is -- out and about when the weather warms up. The Post story also suggests that warm weather may agitate some people, causing them to become more violent.

In a totally unrelated story that has nothing to do with weather, DCist notes that there is talk around town of naming the National Zoo's new baby panda "Butterstick," or rather the Mandarin translation of the word, which was used to describe the size of the cub when it was born last month. While I can think of nothing more adorable than a panda named Butterstick, I'd like to submit an alternate name for consideration, one which I feel you just don't see enough of around here: Ronald Reagan.

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