Rolling ominously across a gray sky with booms of thunder or serenely drifting in a bright blue expanse, clouds are fascinating to watch. But how do clouds get there?

"Cumulus clouds, for example, get their start when their solar energy evaporates water from oceans, plants, and soil by breaking the bonds that hold water molecules together," explains Emily Elert of MinuteEarth. "As the patch of air above collects moisture and heat, cooler, heavier air sinks around it, pinching it off and pushing it aloft like an invisible hot air balloon.”

The entire process is beautifully illustrated in the video below.

Video Credit: Minute Earth

It's interesting to note that clouds aren't formed from only water vapor. Cloud condensation nuclei—which are small particles about 0.2 micrometers big—allow water vapor to condense. These small particles can be pollen, smoke particles or even dust. 

But for a fluffy body that is at least 99 percent water, clouds are not as harmless as they look. As Emily further narrates, "Even in a cumulus cloud, the total energy released from condensation is huge—equivalent to about 270 tons of TNT.”