Wednesday, September 13, 2006

Helping The Weather Man

I love snow. I always have. I can sit for hours and watch it fall. Even when it's dark, I'll sit at the window, and sigh happily to see it float down in the gleaming circle of illumination coming from the streetlamp across the road. I have a very romantic view of snow. Snow is magical, and makes everything beautiful. On the practical end of things, snow is just frozen water coming from ice crystals in the clouds high above. A little warmer, and that snow becomes rain (something which happens often in Portland.) A bit of interference from warm air sneaking its way between upper and lower masses of cold air, and we get freezing rain, which is close to an annual event here in the Rose City, much to my annoyance. It's just not nearly as fun to watch rain freeze as it is to watch snow fall. The other almost annual event here is getting teased by forecasts, telling me there is a seventy percent chance that I'll get to bask in the warm and fuzzy glow that only snow brings, only to have the prediction be wrong. Again. Rain instead. I never believe them anymore. If they tell me it's going to snow, I assume there's a sixty-five percent chance they're wrong. Sixty-five, seventy.

In any case, whether I complain or not, whether it lands as rain or snow, or some other form of precipitation, moisture that comes down here, starts up there, as ice crystals high above us. Did you know, though, that lightning also comes from that ice in the sky? Well it does. A NASA report that I got today, written by Dr. Tony Phillips, confirms that an electrical charge is built up when different sized ice crystals in clouds rub together. Enough of that electrical charge makes lighting. By NASA's account, lighting heats the air in its path to three times the surface temperature of the sun. So much heat coming from ice is a bit of a mental leap, but according to Dr. Phillips, the science works. It just takes an awful lot of ice to produce the effect.

The awful lot of ice part is where this information gets useful. Counting lightning flashes, as it turns out, is an accurate predictor of how much ice is in clouds. After a three year study, by the National Space Science and Technology Center in Huntsville, Alabama, using radar equipment that measures the amount of ice in clouds, and an optical detector to count lighting flashes, scientist Walter Petersen and his colleagues have determined a definite correlation between the amount of ice a cloud contains, and the amount of lightning it produces. The correlation held firm over land, sea, and coast. This information is going to help weather reports become more accurate--maybe even in Portland:

Now that the correlation between ice and lightning is so well established, it can be put to good use. Petersen explains:

"Computer programs we write to predict weather and climate need to know how much ice is in clouds. The problem is, ice is hard to track. We can't station a radar over every thundercloud to measure its ice content. To improve our computer forecasts, we need to know where the ice is."

Lightning can help. "Because there's such a strong correlation between lightning and ice, we can get a good idea of how much ice is 'up there' by counting lightning flashes."

According to Petersen, the optical detectors, called LIS (lightning imaging sensor), are inexpensive, and can be located on Earth, or in orbit, so, now that the correlation is clearly understood, the models on which they base weather forecasts could start giving a more accurate view of whatever weather is headed toward your area. If they place lots of LIS devices all around the globe, they can start counting all those lightning flashes. More lighting flashes mean more ice. More ice means more potential precipitation. It's not a stretch to connect that how much ice is in the clouds affects how much precipitation we get down here. Little ice means little chance of rain, snow, sleet, etc. Lots of ice could mean lots of rain, snow, sleet. I'm saying could mean, because even if the ice is there, it's not a guarantee that it's coming down in any given location. They'll have to figure out some other method to predict exactly where the clouds will release their burden. I actually think they ought to skip that step in weather science, and just go straight to a weather control device. That way maybe Portland could get some snow for a change, instead of freezing rain.

This new information and technology could be changing the accuracy of weather predictions in the not too distant future. I predict it will. I forecast a seventy percent chance of increased accuracy. Sixty-five, seventy. Somewhere in there. Unless the wind shifts, or the ocean currents change path, or a butterfly starts beating its wings somewhere over China. Yeah, I think the new info will help. Fifty-five, sixty percent chance. Maybe.