Flat Clouds, Round Clouds, Wispy Clouds: The Science Behind Clouds and Their Shapes


Look up or out your window right now and, chances are, you’re likely to see a cloud in the sky.Depending on outdoor conditions, you’re more likely to see a sky filled with clouds than a cloudy day. You might notice that while clouds can remind you of certain things, they are rarely the same size or shape with the clouds around them or the types of clouds you see in pictures taken elsewhere.

You may not know it, but there’s actually a science behind the cloud shapes you see. For instance, flat-bottom clouds exist because it marks the boundary where water vapor condenses. To further explain this and why clouds have different shapes, we first need to go back to our middle school science lessons and get a recap on the water cycle.

Let’s Recap: The Water Cycle

Image via World Atlas

Out of the various environmental cycles we learned in second grade biology, the water cycle has to be the easiest because, unlike nitrogen and other cycles, we can see the effects of the water cycle on an average rainy day.

It starts with water evaporating from large bodies of water, ice and snow, water from plants, and moisture in the soil. These turn into water vapor that rise up the atmosphere. Eventually, it will reach a certain height where the air is much cooler, causing the vapor to condense into water droplets that combine into what we see as clouds.

These clouds move through the air currents and can continue to grow to a certain point by combining with other clouds. Aside from water droplets, there are also dust, pollen, and other small particles carried up by the water vapor. Eventually, there comes a point when the clouds become too heavy to carry all the water droplets, which causes precipitation or rain.

How Are Clouds Formed?

During evaporation, the moist air rises upward to the part of the atmosphere where it’s colder. However, there isn’t always a straight line separating air that’s still warm from air that’s cold enough to condense water droplets. Clouds with flat bottoms are fairly simple to determine where the altitude water vapor condenses because we know for a fact that this flat line is where condensation takes place. Once enough vapor is at the bottom, newly formed water droplets push the existing clouds upwards, hence why flat-bottom clouds often have fluffy tops.

The most basic types of clouds include:


Image via Pixabay user PublicDomainPictures

The most common type of clouds, cumulus clouds are the typical cotton candy-looking clouds with a puffy shape but usually flat bottoms. Cumulus clouds are often seen during fair to warm weather and hardly ever rain.  They are often low-level compared to hotter temperatures where water vapor needs to rise higher to condense. Under cumulus clouds, there are plenty of forms under it, including stratocumulus, altocumulus, and cirrocumulus.


Because cumulus clouds do not rain, they remain in the atmosphere often surrounded with other cumulus clouds. Eventually, it will either merge with other cumulus clouds or continue to collect water vapor, pushing old clouds further upwards into the atmosphere. However, there comes a point when these clouds collect too much water droplets that they become too large and heavy to stay in the atmosphere, so these droplets fall as rain.

If you notice cumulus clouds growing bigger and extending higher into the atmosphere, it’s a sign that it may rain soon, especially during the summer seasons. On its lower levels, cumulonimbus still has its flat bottom where you can see the point where water vapor condenses, though it may be a bit difficult to tell due to its size and the wisps around it. Higher up, cumulonimbus clouds are wispier than its dense bottom.


Image via Pixabay user PublicDomainPictures

Cirrus clouds are located high in the atmosphere and are defined as tufty, patchy wisps that are actually water vapor turned into ice crystals falling through the atmosphere. Because of their form and size, they are easily carried by winds of different speeds, thus giving it its curled shape. During the day, cirrus clouds are whiter than any other types of clouds because it isn’t as heavy as other clouds, nor does it carry as much droplets. Because of its thin and wispy form and not like opaque clouds, during sunsets, they tend to take the color of the sunset, giving it a golden-orange hue.

While this indicates that there isn’t much water droplets, if you find that these clouds are getting warmer and thicker, it could mean a warm front is approaching and you should expect rain within the next 12 hours.

Why Don’t Clouds Look Alike?

These three aren’t the only types of clouds. In some locations around the world, the winds are unlike other parts of the world that you might only see certain cloud formations in specific parts of the world. You might even find clouds that look like tornado funnels (but aren’t a warning of a nearby tornado) or a huge wall of clouds.

Image via Pixabay user Ruwadium

Clouds look differently due to a number of factors: from the amount of water vapor in the air (the clouds over a rainforest look different from the clouds in a desert), the climate of a location, the winds, and the type of air. And even if two places have identical settings, there’s no predicting how water vapor moves in clouds, which is why the shape of one cloud won’t be totally the same with another cloud created in the same environment.

There’s a lot more complex topics in the science behind clouds, how they’re formed, and why they look like the way they do. What you should know, though, is that clouds are a fairly good indicator of the likeliness of rain. So, if you see few or regular-looking clouds on a sunny day, it’s unlikely it’s going to rain. But if you notice that the clouds are darker, heavier, and appear to cover nearly the entire sky, be sure to bring an umbrella for the likeliness that it’s going to rain. It can’t predict when or if it will rain, but it’s a good indication for everyday use.


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