Weather Break -- Can't We Do Something About All This Cold Weather?

The following is a transcript of the Weather Break radio show for Monday, January 28, 2008. The program was written by Dr. Jon Schrage.

All last week, thousands of meteorologists from around the world gathered in New Orleans, Louisiana for the Annual Meetings of the American Meteorological Society. Of course, this also coincided with the outbreak of extremely cold weather across most of the United States. You know, Mark Twain wrote that, "Everyone talks about the weather, but no does anything about it." Well, obviously, there was a LOT of "talking about the weather" last week, and you can probably imagine that lots of people quipped that we should "do something about" the subzero temperatures. So, why can't scientists control the weather?

Well, firstly, in some small ways, we CAN at least INFLUENCE the weather and climate of a region. Changes in the use of the land by people produce changes in the climate and weather patterns that a region experiences. For example, building cities like Phoenix and Las Vegas out in the desert has produced a moistening of the climate of those regions. While those particular cities do a reasonably good job of managing water and encouraging conservation, there IS more evaporation from those cities than there is in the surrounding countryside, and this increased humidity increases annual rain rates and cloud cover. Similarly, breaking the sod to raise cash crops in the Midwest is believed to have produced some climate change in the 19th century-- in fact, the pioneers were counting on it! Most of the pioneers believed that the lands of the central United States were too dry to raise crops, but conventional wisdom at that time was that "the rain follows the plow"; in other words, they believed that the land would become more moist once the sod was broken. We'll have more information about the idea that the rain follows of the plow on Friday's episode of Weather Break.

That being said, I think that we're all in agreement that this isn't what people mean when they jokingly ask the meteorologists if they could do something about the weather. Rather, they mean that they are wondering why it isn't possible to just flip a switch and make the weather do something that we want it to do, like increase the temperature at the surface on a cold day.

Well, the primary reason why we can't control the weather is that the atmosphere is really big. Air may seem light, but there's a lot it in the atmosphere, and it would take a lot of energy to heat the air up. For example, let's suppose that you wanted to make a system that somehow used a satellite in space to heat up the air and make cold winter days a little warmer. For example, maybe there are lasers on the satellite or something like that. Okay, let's say that you wanted to heat up all of the air over the United States by 10°F, and just for the sake of argument let's say that you wanted to heat the air from the surface up to a depth of just 10 m. That would mean that you would need to heat up a volume of air the size of the United States and as deep as a four story building. The amount of heat needed to increase the temperature by just 10°F would be 5 times 10 to the 17th Joules--that's the equivalent of 144 megatons of TNT, or about the same about of energy as would be released by detonating about 430 ballistic missiles! I don't know about you, but I'm GLAD that we don't have satellites in orbit that can deliver that kind of energy!

That kind of "brute force" weather modification strategy really can only work on the very smallest of areas. For example, farmers in the South can protect their orchards from frost by setting up so-called "orchard heaters", which help keep the temperature from falling too far below freezing on a chilly night. It works, but it's expensive--farmers in the Midwest couldn't afford to use a strategy like that to protect corn and soybeans, for example, because an acre of soybeans doesn't produce nearly as much money as an acre of oranges.

Even if there was a way in which somehow meteorologists could control the weather, it wouldn't be a very good idea, simply because it would be impossible to predict all of the unintended consequences of weather modification. Besides, just because a particular weather pattern is unpleasant or uncomfortable for people, that doesn't mean that it isn't important for some other aspect of the environment. Winter storms may cause travel headaches for people trapped at airports, but the moisture from these storms can be very effective at soaking down into the soil, providing moisture to crops in the summer. Subzero temperatures are unpleasant, but some plants have seeds that need cold temperatures in the winter in order to germinate in the spring. Meteorologists and atmospheric scientists tend to be pretty smart, but there's no way they could possibly anticipate all of the possible things that would go wrong if they tried to control the weather on any large scale.