Precipitation comes in many forms, but it all comes from the same general process.
In this video lesson you will identify different types of precipitation, as well as how precipitation forms in the atmosphere from condensation.
What Is Precipitation?
Believe it or not, a heavy downpour in the tropics, a blizzard in the Northeast, and a daylong drizzle in the Pacific Northwest are all related to each other. This is because they are different types of precipitation, which is water that falls back to the ground after condensing in the atmosphere. That means that any type of falling water, be it liquid or frozen, is falling as precipitation. Heavy or light rain, sleet, snow, drizzle, and hail are all types of precipitation.However, fog and dew are not considered precipitation because these two processes are actually water condensing.
As dew, it is condensing on objects. As fog, it’s condensing in the air, but low to the ground. Let’s look at how this works a bit more closely.
How Precipitation Forms
Precipitation only comes down to the ground after it condenses in the atmosphere. Condensation is when water vapor turns to liquid water.
We are surrounded by water vapor – it’s an important component of the atmosphere. But if it changes back into liquid water and builds up around dust particles in the air, we get clouds. If the cloud droplets get heavy enough, they fall back to the ground for the very same reason you would – gravity!Fog is just a ground-level cloud.
It’s created by water condensing around dust particles low to the ground instead of high in the air. Dew is also condensation, but on objects on the ground like leaves, cars and windows instead of dust particles in the air.So why does some water fall back to the ground and other stays as a gas in the atmosphere? This has to do with air movement from the ground. When warm air rises quickly into the atmosphere, this is known as an updraft – literally air rising upward. Warm air holds more moisture than cool air, so it takes water up into the atmosphere with it.
However, once the warm air rises, it cools and shrinks. The water vapor in the air gets squeezed out as liquid water and builds up around dust particles, forming our cloud.Usually, clouds do a pretty good job of holding onto their water because they are wider than they are tall. So any falling water droplets only fall a very short distance before being swept back up into the cloud by the updraft.If the cloud forms vertically, though, this means that the falling water droplets have farther to fall before the updraft gets a chance to whisk them back into the cloud. When this happens, we get the opposite of an updraft, called a downdraft.
This is just cool air falling through the atmosphere as it gets dragged down by the falling water.As you can see, water droplets in clouds are very friendly, and they like to not only take cool air with them, but other droplets as well. As they fall, they pick up other droplets, grow in size and become too heavy once they do finally hit the updraft. This is when gravity takes over and carries these droplets back to the ground as precipitation.Precipitation and condensation are important parts of the water cycle, which is the natural cycling of water on Earth. If all the water vapor in the air just stayed in its gaseous form instead of precipitating, our rivers, lakes and oceans would dry up.
And remember, precipitation depends on condensation, so we can’t have rain unless those droplets form in the first place!
Precipitation, which is the falling of water back to the ground after condensing in the atmosphere, occurs all over Earth and in many different forms. A heavy downpour, a light drizzle, snow, sleet and hail are all types of precipitation. Be it falling liquid water or falling ice, it’s all the same process.Precipitation can only occur after condensation, which is when water turns from a gas to a liquid. The atmosphere is filled with water vapor, which is water in a gaseous state.
Sometimes this water vapor cools and builds up on dust particles in the atmosphere, forming a cloud. An updraft, which is warm air rising up into the atmosphere, helps a cloud hold onto its water particles. The particles get pulled down by gravity, but since most clouds are wider than they are tall, the water droplets don’t have very far to fall before being pushed back up into the cloud by an updraft.However, if a cloud is taller than it is wide, this means that the water particles have much farther to fall before hitting the updraft. As they fall through the cloud, they convince their other water particle friends to come with them and build in size. Cool air likes to tag along, and this cool air falling in the atmosphere is known as a downdraft since it’s falling downward.
If the water particles build up enough, they become heavy enough that gravity overpowers the updraft and pulls them back to the ground as precipitation.This is why we don’t consider fog and dew to be precipitation – they aren’t falling water! Dew is simply condensation of water on objects on the ground, while fog is a ground-level cloud. There’s no water falling from either of these, just condensation at our atmospheric level.
After watching this lesson, you should be able to:
- Identify different types of precipitation
- Explain how precipitation forms from condensation in the atmosphere