Saturday, September 17, 2011

Science on a Saturday Afternoon

Since I couldn't be with the Science Cheerleaders at the NYC Maker Faire today, I decided to go to a science event here in Huntsville. However, I did see that Dar managed to post a couple of pictures:

University of Alabama-Huntsville, located across the street from the day-job office, was hosting a "Weather Fest" to showcase the school's work in various aspects of meteorology. It was a nice example of "fun" and "science" not being incompatible (rather like the Science Cheerleaders, you might say).

The first thing I ran into was a trailer full of large, technical-looking equipment on it set up in the parking lot outside the Shelby Center. I asked the gent by the trailer to explain things, and he (Ryan Wade) did. He initially took me for a Huntsville Times reporter because I was asking a lot of questions and taking copious notes. Sorry, no. That's just me being me. :-)

Anyhow, the first machine he explained was a high-energy radar that fired its microwave pulses in three directions: toward the zenith (straight up), to the north, and to the east. By collecting data in these three directions, the radar can get a good reading on the atmosphere's temperature, moisture, and wind speed/direction.

Next to that was a radiometer, which passively detects microwaves (heat) generated by clouds, as well as moisture in the air. Between the radar and the radiometer, the meteorologists are able to get a lot more data points, the equivalent of "a weather balloon every minute," which is good, because weather balloons are expensive.

The impressive-looking bulb at the front end of the trailer was a vertically looking, dual-polarized X-band radar, which is what it sounds like: a radar that points straight up and sends pulses into to the sky. What does "dual-polarized" mean? I just learned this while trying to dissect some SERVIR stuff a couple weeks ago, so I'd better go ahead and explain it before I forget. If you've ever seen light waves depicted in science class, they look like waves that go up and down, more or less in the same plane. Well, radiation can be transmitted at almost any orientation (see image below), but human beings will generally detect or transmit radiation--like, say, microwaves--in one of two arbitrary planes, our own personal "vertical" or "horizontal." Most conventional weather radars have transmitted horizontally only. If you transmit radar signals vertically and horizontally, you can get a three-dimensional picture of the objects reflecting back signals to the dish. This is important for detecting the difference between rain, snow, or hail, all of which have different shapes. Another advantage of the dual-polarized radar is that it enables meteorologists to detect debris kicked up by a tornado because such debris would have a much different shape from rain or hail. 

The company responsible for changing over all of the National Weather Service radars from horizontal polarization to dual polarization is Baron Services, which all the UAH folks were very conscious of, because Baron is a Huntsville-based company.

One thing that I wanted to learn because it wasn't entirely clear to me was how tornadoes get formed in the first place--especially after the deadly dose of tornadoes we got April 27 this year. Tornadoes start as a result of a simple physical process: hot air rising and cooler air sinking. Obviously there's more to it than that or tornadoes would happen all the time. Other factors include large temperature differences between the air masses--say, between a really cold arctic air mass from up north and a relatively warm air mass coming up from the Gulf of Mexico in early spring. Instead of some air just rising and other air sinking, the air masses actually start rotating, creating a horizontal column of air in the sky. As the storm front moves forward and the cloud bases (bottoms) move closer to the ground, it is possible for this spinning column of air to turn become vertical, strike the ground, and move forward along the storm's path of forward motion. The tornado continues until it loses energy and dissipates.

So there ya go: your (and my) meteorology lesson for the day.

Another cool bit of machinery was a station wagon I dubbed the "Weather Car," which is its function if not its official name--that would be the Mobile Meteorological Mesonet. Festooned with a variety of instruments, including an annometer (for measuring wind speed), temperature and dew point sensors, and GPS unit, the car can take measurements even while in motion. That's probably a good thing, since a lot of the time the Weather Car can be sent out to chase storms, and probably doesn't want or need to get too close. Still, it looks a little like a practical joke played by the Meteorology Department on a school staff car.

In addition to the big machinery outside, inside the Shelby Center, the UAH Atmospheric Science Department had several display tables and other activities to engage the weather-interested, young and old. One interesting character in all this was The Weather Dude, who sang songs about weather education.

I also was impressed with the student who had a plate with some sort of flammable liquid in it, which she covered with a cylindrical screen that could rotate. The rotation of the air within the cylinder drew up the flames, creating a mini-tornado inside the cylinder.

One thing they were doing at the Weather Fest which I thought was kind of cool, in a science-geek sort of way, was raffling off a rain gauge. I put in for one, but didn't win. Boo.

And of course no weather excursion at UAH would be complete without the launch of a weather balloon. UAH launches a balloon once a week, at 1 p.m. on Saturday. The balloon carries up with it a variety of sensors for detecting the same things that the ground-based radars do: temperature, dew point, moisture, wind speed, and direction. The difference with a weather balloon is that the data is collected on-site, from ground to 110,000 feet (~20.8 miles or 33.5 kilometers). The Weather Fest provided a good opportunity for the university to explain what their role is with meteorology and atmospheric science, which of course brought the local TV stations, which in turn provided an opportunity for Huntsville Mayor Tommy Battle to make an appearance.

The Weather Fest also included snack and drink concession tables, a Chik-Fil-A table and one of the CFA cows walking around for pictures, a guy dressed up as a tornado character, mini-golf and activity tables for the kids, a guy selling storm/cloud photography as art, a student with a Tesla coil and a lot of things that could generate an electrical arc, and a TV with video from WAFF from April 27. A couple of side rooms had lectures at them, and I attended a couple, but was a little too caught up in all the other stuff to sit still. So all in all, it was a good event, but I'll bet it would've been even better with a few of the Science Cheerleaders around. The closest we got was that I saw a pom-pon on the Atmospheric Sciences table. Oh, well. Goooo Science!

1 comment:

Dauna said...

This was an awesome read, Bart. Thanks so much for posting it. I love the way you write!