What’s the cloud of gas exploding in the air? Turns out it’s what happens when you combine boiling water with liquid nitrogen. NIST researcher Angie Hight Walker demonstrates a radically cool experiment of “making thunder” by quickly adding the boiling water, which can be considered lightning, to the very cold liquid nitrogen (having a temperature of -196 C or 77 K) simulating the atmosphere. The whole process makes a beautiful cloud of water vapor. The cold nitrogen cools the air around it. Jus