photo by Aaron Burden via Unsplash

by stephanie hobby

Fling a potful of boiling water skyward in these temperatures, and you’ll get a pretty sweet cloud of tiny ice crystals. But what on earth is going on here? 

“When it starts dropping to 10 or 20 below, that cold air is very dense, and it doesn’t hold moisture very well,” said meteorologist Matt Elwell. “If you have boiling water, it’s already close to evaporating, so as you throw it into that cold, dry air, it immediately changes from that evaporating liquid into ice.”

The boiling water is essential; it’s energized and less dense than cold water. (You can picture the molecules zipping around and bouncing off each other.) When you hurl hot water into very dense, cold, dry air, the frigid air flashes into those spaces and surrounds the droplets. There’s more surface area of water exposed to the dry air, so it freezes instantly. 

This is a great way to demonstrate the three states of water. It starts as a boiling liquid, escapes the pot as steam (gas), and very rapidly turns into tiny solid ice crystals.

IMPORTANT: This is a really fun family activity, but safety precautions should be taken to avoid getting burned. 

1. Adults should be the ones handling the boiling water. Others need to watch from a distance, as there is still potential for some extremely hot water to remain and burn someone. Use a pot holder to take the water outside. 
2. You need to pay attention to which way the wind is blowing, and make sure to throw the water away from you, not straight up in the air over your head. 
3. The temperature needs to be lower than 10 degrees Fahrenheit below zero; otherwise, you risk getting splashed with boiling water. 

Never miss an issue, check out SLM's digital editions here!  

related articles: