How big are clouds? Like, how much geographical space could they cover? A town? A city?
In: Physics
Clouds can be lots of different sizes, and it can be tricky to say where one ends and the next begins. many are on the scale of a large town or bigger, certainly if it’s one that can carry rain. If you want to estimate how big one is, if it’s nearish to mid-day, you can just look at it’s shadow.
I thought of this analogy recently that feels right at home for ELI5.
Turn on a lamp in a room, which is a little ways away from a wall. If you put your hand near the lamp, the shadow of your hand becomes very big. If you put your hand near the wall, the shadow will be almost the same size as your hand.
The same would happen with clouds. Clouds are very very close to the Earth, compared to the Sun. So when it’s sunny with some clouds, if you can see the shadow of the cloud on the ground, that’s pretty close to how big the cloud is.
Clouds are enormous. Many, many tons of water, made up of millions of tiny droplets suspended in flowing, moving air. They’re so big that it’s hard to wrap your head around how big they actually are. But not impossible.
Relevant [XKCD](https://xkcd.com/941/)
well, look [here](https://i.imgur.com/qwwTHfA.png)
those are just some rain clouds over Germany. so judge for your self how big they can be. or look at satellite pictures of Earth covered by clouds
Fun fact. The shadow they create is roughly the size of the cloud. Their distance to the sun isn’t enough to actually make a difference in shadow size. Height varies obviously
Also, when clouds move, are they actually constantly eroding at the back and forming at the front, or do the edges remain intact and they physically move through space? If you see what I mean
Big and HEAVY
“They may look all light and fluffy, but the reality is that clouds are actually pretty heavy. Researchers have calculated that the average cumulus cloud – which is that nice, white fluffy kind you see on a sunny day – weighs an incredible 500,000 kg (or 1.1 million pounds!). “
https://www.sciencealert.com/this-is-how-much-a-cloud-weighs
Pilot here.
There is no theoretical limit to how big clouds can get in the horizontal plane (There is a limit in the vertical, to about 50’000 feet because air pressure drops away. No air pressure = no cloud). If the environmental conditions and earth surface allow for it, they can be huge, in both the vertical and horizontal planes. However a large cloud that exists for many miles in the horizontal plane tends to actually be made of lots of smaller clouds that clump together. Aviators generally only consider clouds to be “Big” when they are big in the vertical plane.
As pilots, the cloud we fear is a type called “Cumulonimbus”. In terms of size these things can be monsters, stretching as high as 40’000 feet in altitude, and they have been sighted higher (Unusually). They are the type of cloud that brings rain, thunderstorms and the only cloud that can form hail.
We have a nickname for them…”Charlie Bangers”…from their short weather code of “Cb”. For pilots, they are the universal “Go around or go back” sign and no matter what you fly, you do not enter them. Period.
There are three main ways a cloud can form but the typical one is when formed by moisture in the air that “Clumps” together when the air is rising and begins to cool and the pressure drops. Because warm air carries more moisture than cold air, the air holding the water vapour has to be at a certain temperature first and as it gets higher and cools it meets something called the “Dew point” which is where the temperature drops to a sufficient level the air can no longer hold it.
Clouds form a lot easier when there is pollution, dust or some kind of particulate in the air for the water molecules to cling to.
Oh and a fun fact. Fog is actually cloud. It’s just the temperature and pressure is just right for the dewpoint to be close to the ground.
If you want a real world example of how big cloud can be, I once took off from Berlin and did not see a break in the cloud till the coast of France.
I just wanted to share that I installed the Cloud-to-butt extension in chrome and yours is the first post that I noticed it change and I was very confused and laughed pretty hard. X) [https://imgur.com/a/7LiHCde](https://imgur.com/a/7LiHCde)
How much water does the average fluffy cloud hold? 10 buckets? An in-ground swimming pool? A lake?
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