This warming is in addition to carbon dioxide's better-known effect as a heat-trapping greenhouse gas. For scientists trying to predict global climate change in the coming century, the study underscores the importance of including plants in their climate models.
It is a physical change. All phase changes are physical, not chemical. The chemical composition of water does not change when it changes from a liquid to a gas, or for that ma â¦ tter, to a solid.
It's used to turn the water into steam (the technical term for that energy is the latent heat of vaporization), and the steam stores that energy. It's a lot of energy: 1 gram of steam has enough energy to raise 7 grams of water from room temperature to boiling. When steam condenses back into water on the cooler surface of food, it gives that energy back, quickly heating the food surface. This is why steam can burn your skin badly and quickly. On the other hand, steam isn't very dense--in fact, it's over 1,600 times less dense than water--and, as soon as the surface of the food reaches the same temperature as the steam, you no longer get the huge benefit from condensation.