Why do clouds float? Has that question ever crossed your mind? You go for a walk and you see those big, fluffy clouds hovering right above your head. Even though the average cumulus cloud weighs 1.1 million pounds, they are capable of defying the laws of gravity?
So, how exactly do they manage to do that? Well, let’s learn a few things about clouds and how they work.
First of all, clouds are full of water and, in fact, there are millions of pounds of water floating above your head. But wait…! Air is lighter than water and water doesn’t float. To understand how this works, we need to first understand how clouds are formed in the first place.
Clouds are composed primarily of small water droplets and when it’s cold enough, they form into ice crystals. So, the vast majority of clouds that we see every day are composed of water droplets and/or crystals that are too small for gravity to have an effect on them. Because of this, the particles continue to float.
To better understand this, let’s use an example. Try dropping a feather and a baseball. We all know that the baseball will quickly fall to the ground while the feather will gradually flutter to the surface.
Now, compare a feather to a dust particle. The dust particle will take much longer than the feather to reach the surface since even the slightest movement of air is enough to keep the dust particle suspended.
The water molecules that form clouds have the same tendency. As they get heavier, they start to come down. However, because the Earth is constantly being heated up by the Sun, warm air rises because it expands and becomes less dense.
So, the column of warm rising air which is pushing upwards will come in contact with the tiny water particles which are trying to fall down under their own weight and keep them up there.
This is why clouds have a flat bottom, since that’s the point where the warm air coming upwards and the water molecules going downwards balance each other out.
When the saturated volume of air cools, or when the atmospheric pressure drops, the air is no longer able to hold the water molecules. Thus, the excess amount of water vapor changes from its gaseous state into a liquid or solid ice.
The process of water changing its state from gas to liquid is called condensation. When the water changes its state to solid, the process is called deposition. These two processes are how clouds form.
Now that you know how clouds are formed, it brings us to the next question. How does rain fall?
Rain is an important part of the water cycle. Rain occurs on other planets in our Solar System but it is different than the rain we experience here on Earth.
For example, rain on Venus is made of sulfuric acid and due to the intense heat it evaporates before it even reaches the surface! Rain also allows us to create electricity through hydropower.
So, how and why does it rain?
Rain falls from clouds in the sky in the form of water droplets, this is called precipitation. Within a cloud, water droplets condense onto one another, causing the droplets to grow. When these water droplets get too heavy to stay suspended in the cloud, they fall to Earth as rain.
But then again, what makes it snow?
The process is the same as the formation of rain. However, in the case of snow, it occurs when tiny ice crystals in clouds stick together to become snowflakes.
If enough crystals stick together, they’ll become heavy enough to fall to the ground. Snow is formed when temperatures are low and there is moisture in the atmosphere in the form of tiny ice crystals.
So, next time when someone asks you why clouds don’t fall to the ground, you tell them that clouds are composed primarily of small water droplets.
And the reason why these big chunks of clouds don’t fall to the ground is because the air below is even heavier, pushing them back up.