Meteorologist Ray Petelin is back with another home science lesson!
- Hey, Ray!
- That's so cool.
RAY PETELIN: We've talked about how each snowfall is different. But how each snowfall is created is different, too.
ELIZABETH PETELIN: So there's more than one recipe for snow?
RAY PETELIN: Exactly. There are bigger sized systems that impact a large area. We call those synoptic systems. Then there are small-scale weather systems that impact localized area. We call those mesoscale systems. That's our subject today.
ELIZABETH PETELIN: Mesoscale weather?
RAY PETELIN: Well, a type of it-- lake effect snow. It's probably the most known small-scale type of weather in our region because it has such a big impact. And the first ingredient for lake effect snow is a lake.
ELIZABETH PETELIN: Ha, ha, ha. We have a comedian over here.
RAY PETELIN: More precisely, a lake that is warmer than the air above it. When you lose 55 degrees between the water surface in a mile up in the atmosphere, you start seeing the potential for significant lake effect snow. When the air is colder than the water, you get--
ELIZABETH PETELIN: Evaporation.
RAY PETELIN: That's right. And convection is the other part. You can see that here. The water evaporates in the cold air, and the heat causes it to rise. That's what convection is. The warm parts move up; the cold parts move down.
ELIZABETH PETELIN: We're missing something here. If you're only going up and down, you're keeping everything over the lake.
RAY PETELIN: Wind is the next big factor. You need wind to push that moisture towards land. And wind direction and distance is very important. We call wind that travels a long distance a fetch.
ELIZABETH PETELIN: Dad, stop trying to make that happen. It's never going to happen.
RAY PETELIN: It is so fetch, though. As that wind or fetch travels a long distance over water, it picks up more moisture. The more moisture it picks up, the more moisture that can be condensed and changed to snow. Most people in our area look to Lake Erie for a lake effect snow. But when other lakes are involved, especially Lake Huron, we can get some pretty good snow down here all because of that fetch.
And the other big lake effect ingredient is orographic lift.
ELIZABETH PETELIN: Did you just make up a word?
RAY PETELIN: Uh, no. Orographic lift is caused by land creating friction and forcing air upward. When wind blows across lakes, there's not much in its way. So it can move pretty freely. Once the wind starts to encounter land, though, it slows down. When that happens, our convection or uplift is enhanced.
Think of it like this-- the moisture starts to pile up because of friction. And that forces the air upward even more, condensing even more and making more snow. And this process will continue until the lakes freeze over. That's like putting a lid on a container.
ELIZABETH PETELIN: The Elizabeth effect snow is way more fun.
RAY PETELIN: The Elizabeth effect grounding won't be. Reporting from home--
ELIZABETH PETELIN: I'm Elizabeth Petelin.
RAY PETELIN: And I'm meteorologist Ray Petelin.
ELIZABETH PETELIN: No!