| A | B |
|---|
| solar energy | energy from the sun |
| rotation | One complete spin of Earth on its axis |
| revolution | the 365 1/4 day trip Earth takes around the sun each year |
| latitude | the distance north or south of Earth's equator |
| tropics | regions close to the equator |
| freshwater | water without salt |
| glaciers | large areas of slow-moving ice |
| surface water | water that is found in Earth's streams, rivers, and lakes |
| precipitation | water that falls to Earth's surface as rain, snow, sleet, or hail |
| groundwater | water found below Earth's surface |
| water vapor | water in the air as an invisible gas |
| water cycle | the movement of water from Earth's surface to the atmosphere and back |
| landforms | shapes on the planet's surface |
| continents | large landmasses |
| plate tectonics | a theory suggesting that Earth's surface is divided into slow-moving plates, or pieces of Earth's crust |
| lava | magma that reaches the Earth's surface |
| earthquake | sudden, violent movements of Earth's crust |
| weathering | the process by which rock is broken down into smaller pieces |
| erosion | the movement of sediment from one location to another |
