| A | B |
|---|
| equator | imaginary line around Earth that divides it into hemispheres |
| atmosphere | envelope of gases surrounding Earth |
| hydrosphere | water on Earth |
| lithosphere | land on Earth |
| hemisphere | half of Earth, either north or south |
| ozone | umbrella for life, absorbs harmful UV radiation in the stratosphere |
| nitrogen cycle | movement of nitrogen from atmosphere to soil to living things and back to atmosphere |
| troposphere | layer of atmosphere closest to Earth |
| convection currents | air movements caused by warm, less dense air rising and being replaced by cooler, denser air |
| stratosphere | the layer of the atmosphere that is extremely cold and contains the jet stream |
| jet stream | very strong eastward winds that blow horizontally around the Earth |
| mesophere | this layer helps protect us from the meteroids |
| thermosphere | this layer has very thin air at a very high temperature |
| ionosphere | lower layer of thermosphere that contains electrically charged particles |
| exosphere | upper part of thermosphere, has very thin air |
| ions | electrically charged particles |
| magnetosphere | area around Earth that extends beyond the atmosphere |
| Van Allen radiation belts | region with high radiation caused by captured protons and electrons |
