Dry ice is carbon dioxide (CO2) in its solid form. At temperatures above -56.4 °C (-69.5 °F), dry ice changes directly from a solid to a gas, without ever being a liquid. This process is called sublimation. When dry ice is put in water it accelerates the sublimation process, creating clouds of fog that fill up your dry ice bubble until the pressure becomes too much and the bubble explodes, spilling fog over the edge of the bowl. Dry ice is sometimes used as part of theater productions and performances to create a dense foggy effect. It is also used to preserve food, freeze lab samples and even to make ice cream!