If you’ve ever been close enough to lightning when it strikes you may be familiar with the startling high frequency thunderclap or crack it makes. But the high frequency soundwaves of the clap are attenuated by their travel through the air away from the source so that from a kilometre or so away all you hear is the growling of the thunder rumbling away as it clatters and rebounds off everywhere it hits.

I learned about this from Randall Munroe’s fun book How to: Absurd scientific advice for common real-world problems.

Thunderclap or rumble

Nature’s greatest snow machine, where crazy amounts of snow can fall in huge snowstorms on the downwind — leeward — side of a lake. Where the effect is pronounced, such as on the East of some of the Great Lakes in the US, it can generate regions known as snow belts because of the amount of snow they receive.

It works kind of like this: cold air blows over a lake. As the cold air passes over the warmer lake it picks up water vapour from the lake and it warms. This causes it to rise and in turn cool, such that when it reaches the downwind side of the lake it is now a lot of cold moist air which can cause some incredible snowstorms, like 2–3 inches of snow per hour. Satellite pictures like these show it in action pretty clearly. If the land rises after the lake the air can cool faster and increase the effect — and also cause a rain shadow — and if there’s a whole lot of convection and the air is rising fast you can get what’s called thundersnow — a thunderstorm in a snowstorm. I know.

Find weather interesting? Me too. You might also be interested in: Dirty thunderstorms, thunderclouds, yesterday’s weather (applying weather forecasting to software engineering), rain shadow, lenticular clouds, know your cirrostratus from your altocumulus, and British weather.

Lake-effect snow

Caused by ash and rock interacting inside a cloud instead of ice particles. As you can imagine you can get this with volcanoes which can be pretty spectacular. Here’s more about how lightning forms inside a thunder cloud, the regular kind.

Sketchplanations tagged with thundercloud