| A | B |
|---|
| atmosphere | the layer of air that surrounds the Earth |
| air pressure | air pressing down on Earth's surface |
| troposphere | the layer of the atmosphere closest to the Earth |
| stratosphere | the layer of the atmosphere that contains ozone and is located above the troposphere |
| greenhouse effect | the warming of Earth caused by the atmosphere trapping heat from the sun |
| air mass | a huge body of air which all has similar temperature and moisture |
| front | the border where two air masses meet |
| cirrus | wispy, thin, feathery clouds at high altitudes |
| cumulus | puffy cotton ball clouds at middle atlitudes |
| cumulonimbus | dark, towering clouds that bring heavy rain |
| stratus | thick, gray clouds near Earth's surface |
| barometer | instrument that measures air pressure |
| humidity | amount of water vapor in the air |
| hygrometer | instrument that measures humidity |
| the 4 layers of the atmosphere | thermosphere, stratosphere, mesosphere, and troposphere |
| the two properties of air masses | temperature and moisture |
| the layer of the atmosphere where most weather occurs | troposphere |
| warm air | is forced up by cool air and has lower air pressure |
| this cloud brings heavy rain | cumulonimbus |
| When a cold front passes through | it will be stormy and then it will be cooler |
| what kinds of changes in weather occur? | there are changes in temperature, air pressure, wind, and precipitation |
| what causes the changes in weather? | the uneven heating of the Earth by the Sun |
| What steps should you take if an alien is coming after you? | Great big ones! |
