Weather Whys: Why do clouds form at the same level?

Weather Whys

Have you ever looked at clouds in the sky and wondered why they all seem to form at the same distance from the ground? There’s a scientific reason why that happens!

Clouds form when saturated air rises through the sky…but it all starts at the surface. A parcel of air at the Earth’s surface has a specific temperature, pressure and humidity.

As this parcel of air rises, it will undergo some changes. The temperature change is the most important. As the air rises, it cools, and cooler air is capable of holding less water vapor than warm air. As the air cools, the saturation of that parcel will rise. Eventually the air will rise and cool so much that the parcel will be 100% saturated.

If the air rises above this level, it won’t be capable of holding all the water vapor it contains. This level is called the LCL, or lifting condensation level.

If the air rises above the LCL, some of the water vapor will be forced to condense. This forms a cloud rising from the LCL, creating a flat bottom on the cloud. The parcel will continue rising and condensing water vapor out, and the cloud will continue to grow until the air parcel dries out or stops rising.

Because the air in the same area will have similar conditions (temperature, pressure, humidity), the LCL in that area will be the same. This is why clouds all seem to form at the same level.

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