What happens when 200⁰F water meets –321⁰F liquid nitrogen? A big boom and instant clouds! Frank Hardin, Ph.D., from Noble Academy demonstrates the explosive effect with a tub holding several liters of liquid nitrogen and the assistance of a pitcher of hot water.

Good fun, but what's the science? The air around us contains water vapor, the gaseous phase of water. When water vapor cools, it condenses into a liquid phase that we can see – that's fog or clouds.

In the demonstration, you will see hot water poured into liquid nitrogen. The extreme temperature difference (approx. 500⁰F) rapidly vaporizes/boils the liquid nitrogen. The invisible vaporized nitrogen gas expands and the rising nitrogen plume immediately cools the water vapor in the air above, causing a cloud to form. The rapid evaporation of the liquid nitrogen also forces the visible water vapor cloud upward at an alarming rate accompanied by an audible BOOM.

Noble Academy is a student education and outreach program of The Samuel Roberts Noble Foundation in Ardmore, Okla. Noble Academy provides educational programs to raise awareness of today's youth about the role and importance of science and agriculture in society.