Why Do Clouds Float and Not Fall out of the Sky? 

Source of pictures: Pixabay.com

After lunch, Daniel and Mom were sitting together on a bamboo bed, playing checkers. Daniel thought so hard, but mom was only a few steps away from winning. Looking at Daniel's unhappy face, Mom put the chessboard away and patted him on the back, "You are a big boy now, Daniel. It is no big deal." Daniel lowered his head in embarrassment and said, "It's ok, Mom. I just need more practice." Then Mom said, smiling, “Ok, I am waiting for your challenge.” Then they lay in the bed and looked out the window at the clouds.

Daniel looked at the floating clouds in the sky. Suddenly, he asked curiously, "Mom, how heavy are the clouds?"

Mom thought for a moment and said, "I read a report that said the weight of clouds is usually in tons."

Daniel opened his mouth in surprise and couldn't believe it. "How could they float in the sky and not drop down?”

Mom didn't expect Daniel to ask this question. She thought about it for a moment and then asked in turn, "Do you know what's in the clouds?"

Daniel replied confidently, "clouds are made of water droplets. Our science teacher said so."

Mom looked at the sky and said, "The clouds are in fact widely distributed, and the water droplets in them are tiny, so they fall very slowly, at only about a centimeter per second, and are easily pushed back by the winds blowing up. Also, you know that the two main components of air are nitrogen and oxygen. A water molecule is made up of two hydrogen atoms and an oxygen atom. The molecules weigh less than nitrogen and oxygen. So if the droplets are small and dispersed enough, they can easily float in the air."

Confused, Daniel asked, "Is such a big cloud not as heavy as air?"

"That’s not the case because the weight of a cloud, or air, or any other substance, depends not only on the weight of the molecules that form the substance, but also on the way they are arranged and distributed. For example, although the water we drink is also made up of water molecules, it's heavier than air. The water in a cup can never float in air.”

As they talked, the clouds drifted away, leaving only a clear blue sky. Mom suddenly thought of something and said, "Besides, clouds may also float in the sky because of temperature."

Daniel waited for Mom to continue.

"The warmer the air, the easier it is to go up, and conversely, cooler air will go down. Water vapor in air condenses into tiny droplets when it meets cooler air. And as the warmer air rises, the water droplets may rise with the warm air, and the temperature of the warm air will decrease. When they reach a certain height, the water droplets will be suspending in air in a relatively balanced way."

That made sense to Daniel this time. He did not expect that clouds were not only beautiful, but also so much scientific truth behind them. It seems that clouds floating in the sky is not so simple.

Author: Huang Jing