Week of November 17, 2024 – November 23, 2024
by Elizabeth Suzedell, Environmental Educator
“What’s a fancy word for rain and snow?” This is a question I’ve been asking a lot recently to the Syracuse 3rd graders during their first Nature in the City lesson of the year. The answer is “precipitation.” In this lesson, they learn a lot about water- where it comes from, local watersheds, and the water cycle. There’s never enough time for it, but I always want to tell them about all the other types of precipitation besides rain and snow- especially because we’ve entered into the time of year when it’s possible for us to get four or five different types in one day!
When the air is warmer, we get rain, and when it’s colder, we get snow. If we have mixtures of warm and cold temperature layers throughout the atmosphere, there may be other kinds of precipitation. Sleet is formed when liquid raindrops fall into a layer of cold air, which freezes them into solid ice pellets before hitting the ground. Graupel has a similar pellet shape, but it’s opaque and soft, looking like “Dippin’ Dots” ice cream. This forms when snowflakes fall through a slightly warmer layer with tiny supercooled water droplets, which freeze onto the snowflakes and give it a rounder shape.
All forms of winter precipitation can be dangerous in some way, but none are as damaging as freezing rain. It appears just like regular rain, but when it hits the ground, it immediately freezes, creating a glaze of slippery ice. This occurs when the rain is falling through a very shallow layer of cold air near the ground, so the raindrops don’t have enough time to freeze until they actually hit the surface. If freezing rain continues over many hours, ice layers can get very thick, putting a lot of weight and stress on trees, powerlines, and buildings. If you ever notice that it’s raining even though the temperature is close to 32°F, be wary of freezing rain!
The last form of precipitation to be mentioned is hail. Even though hail is a ball of cold ice, it is NOT a type of winter precipitation! Hail forms during thunderstorms, which we mostly get during the summer. If a thunderstorm has a strong updraft, it will push raindrops high up in the atmosphere where temperatures are below freezing. The droplets freeze and collide with more droplets, so the hailstones grow and grow until they are too heavy to be suspended by the updraft winds. Sometimes, they can grow as big as a golf ball, or even a grapefruit! Hail is often confused with sleet, but they form in very different storm structures and seasons.
Our atmosphere is powerful and dynamic. Small differences in its conditions can give way to big changes in the type of weather we get down on the ground. How many different kinds of weather have you observed so far this fall?