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How Do Clouds Form?

A bunch of thick and fluffy clouds as seen from above.

Have you ever looked up at the sky and wondered how it filled itself with as many clouds as it does? Sometimes, the blue sky is coated in a layer of clouds, while other days, there’s simply not even a cloud present. But, how is this possible? How do clouds even form in the first place?

From what clouds are to what conditions are necessary to have them form, we’ve covered everything you need to know about these complicated sky masterpieces. By the time you’re done reading, you’ll never wonder how those fluffy white clouds got up in the sky again.

What are Clouds?

First, we always want to start with the basics. Understanding exactly what a cloud is is key in understanding how they form in Mother Nature’s clear blue skies.

When you look up and see clouds in the sky, you’re actually looking at water droplets being suspended in the air. Depending on the type of cloud, they may also be made out of ice crystals. Clouds vary depending on the weather in general, as storm clouds will look drastically different than the regular fluffy ones you see on a Sunday afternoon.

Clouds get their terminologies based on where they are in the sky and their shape.

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Types of Clouds

There are so many different types of clouds, but there are three that are the most common. Those are going to be Stratus, Cirrus, and Cumulus clouds.

Stratus Clouds

A beautiful stratus cloud formation.

These are the types of clouds that are low-hanging and cover the sky like a layer. In fact, the word “Stratus” itself comes from the Latin word for “layer,” which makes sense as to why you see this type of cloud over the fog. Stratus clouds do have the potential to produce a little bit of rain or even some snow.

Cirrus Clouds

A bunch od cirrus clouds against a blue sky.

These are those super-thin, wispy clouds you see seemingly sitting atop of the sky. This time, the word “Cirrus” actually translates to “ringlet,” similar to a curly ringlet of hair.

These high-level clouds can form at a lot of different elevations, but they’re most typically found at incredibly high altitudes. Cirrus clouds don’t produce rain or snow–rather, they’re usually what you see on the most temperate days.

Cumulus Clouds

A sky with big fluffy cumulus clouds along with thick storm clouds.

These are the ones you’re used to seeing, drawing, and taking photos of. These are your big, fluffy white clouds that can completely fill the sky above you.

Like in drawings, Cumulus clouds have a bit of a flat base but then puffs out in all directions. Usually, these happy-looking clouds indicate that you’re going to have a good day of weather. Sometimes, though, these Cumulus clouds can transform into larger, denser clouds that can produce rain and snow.

For a more detailed guide about different types of clouds, read our article “10 Types of Clouds in the Sky”

How Do Clouds Form?

Now, let’s talk about how clouds form in the first place. Essentially, clouds form primarily through evaporation and condensation. It’s important to note that different clouds are formed in different ways, though, we’ll detail a quick generic process of how many clouds are created.


It all starts with evaporation. Water droplets from areas like rivers, lakes, and oceans turn into water vapor and are sucked up into the air through this evaporation process.

The higher it gets into the atmosphere, the lower the pressure and temperature are going to drop. When this happens, the water vapor sucked up from bodies of water transforms either back into water droplets or ice crystals. This is where they start the process of condensation.


After water vapor undergoes this temperature and pressure change, it’s going to begin to condense. For easier condensation, these water droplets require a kind of binding molecule, called condensation nuclei.

Most commonly, these are things like dust or pollen that the water picks up during its journey. With these nuclei, the water droplets condense. Thus, a cloud is made.

Condensation is one of the most distinct physical processes in the hydrological cycle of water. Here is an article I wrote where I discuss the important role of clouds in the water cycle.

Necessary Conditions

Other than the two situations mentioned above, there are a few other conditions that are necessary for clouds to form. These are moisture, pressure, and temperature. Again, these may differ depending on the types of clouds that are forming.


Simply put, without moisture, you just don’t have clouds. The more moisture in the air, the easier it is for clouds to form, seeing as though they’re made out of water vapor.

When the air is super dry, and there aren’t areas for the sky to pull water from, you’re likely going to see a lot fewer clouds than in places full of lakes, rivers, and moisture. Moisture is absolutely integral in helping clouds form.


Often, winds will push air up in places with lowered pressure. This drop in pressure is what helps these suspended water droplets condense. Many scientists have explained that when there is too much wind, the wind simply doesn’t have anywhere else to go but up.

This exactly when water vapor is pushed up into the sky, into the pockets with low-pressure. Without experiencing this drop in pressure, so many clouds–including Stratus and Cumulus clouds–wouldn’t be able to form at all.


Some clouds like Cumulus clouds rely on heat to form. Initially, they need the heat from the sunshine to warm the air. Once this air is warmed, it’s lighter in pressure and starts floating up into the atmosphere.

Eventually, as we’ve established, when this water-vapor-filled air rises, the pressure drops. Then, that drop in pressure forms some of the most common clouds you see in the sky.

A sunrise seen from the beach with a massive cloud formation.

Enjoying Your Cloudy Days

Your cloudy days are now more interesting than ever. Understanding how these unique formations are actually formed is crucial to fully appreciate their beauty.

Here, we only just started to cover the types of clouds that you’ll come across, so keep your eyes peeled for less-common, more complex clouds, too. They’re a lot of fun to spot.

More About Clouds…