| A | B |
|---|
| evaporation | liquid to gas |
| condensation | gas to liquid |
| precipitation | any type of water that falls from the sky |
| transpiration | movement of water vapor out of a plant |
| percolation | liquid water passing into earth |
| altitude | distance above sea level |
| density | amount of mass in a given volume of a substance |
| radiation | energy traveling across distances |
| conduction | heat transfer by direct contact |
| convection | transfer of energy by the motion of a gas or liquid |
| troposphere | nearest Earth's surface: weather happens |
| stratosphere | ozone layer |
| mesosphere | most meteors burn up here |
| thermosphere | farthest from Earth's surface |
| ozone | molecule made of three atoms of oxygen |
| greenhouse gases | CO2, methane, water vapor, nitrous oxide |
| greenhouse gases | hold heat in Earth's atmosphere |
| greenhouse effect | keeps Earth warm |
| air pollution | smoke and other harmful materials added to the air |
| smog | combination of smoke and fog |
