| Flap 1 | Flap 2 |
| air pressure | the force of air molecules pushing on an area |
| barometer | any instrument tht measures air pressure |
| weather | the condition of Earth's atmosphere at a particular time and place |
| wind | air that moves horizontally or parallel to the ground |
| global winds | winds that travel thousands of kilometers in steady patterns and last for weeks |
| Coriolis effect | the influence of the earth's rotation on winds and other moving objects over the Earth |
| doldrums | low pressure zone near the equator |
| horse latitudes | high pressure zones located about 30 degrees north and 30 degrees south of the equator |
| trade winds | blow from the east, moving from the horse latitudes toward the equator |
| westerlies | blow from the west, moving from the horse latitudes toward the poles |
| easterlies | blow from the east, moving from the polar regions toward the mid latitudes |
| stormy weather | occurs when cold air of the easterlies meets the warmer air of the westerlies |
| westerlies | bring storms across much of the US |
| horse latitudes | causes weather to be clear and dry |
| jet streams | usually lfow in the upper troposphere from west to east for thousands of kilometers |
| sea breeze | caused by warmer air rising over the land during the day and cooler air blowing from the water |
| land breeze | cooler air blows out from the land and warmer air rises over the water at night |
| winter monsoon | occur in regions where the land cecomes much cooler than the sea during the winter |
| summer monsoon | low pressure builds over the land and warm, moist air comes onto land |
| evaporation | the process by which a liquid changes into a gas |
| energy | what is needed for water to evaporate |
| condensation | the process by which a gas, such as water vapor, changes into a liquid |
| condensation | occurs when moist air cools |
| precipitation | any type of liquid or solid water that falls to Earth's surface |
| humidity | the amount of water vapor in the air |
| saturation | a condition in which the rates of evaporation and condensation are equal |
| unsaturated air | more water evaporates into the air than condenses back into the water |
| saturated air | amount of water that evaporates equals the amount that condenses |
| relative humidity | compares the amount of water vapor in air with the maximum amount of water vapor that can be present at that temperature |
| dew point | the temperature at which air with a given amount of water vapor will reach saturation |
| clouds | condensed water vapor |
| cirrus | appear feathery and wispy |
| cirrus | "curl of hair" |
| cumulus | "heap" or "pile" |
| cumulus | can grow very tall |
| stratus | "spread out" |
| stratus | form in flat layers |
| cirrus | form in very cold air at high altitudes |
| cirrus | made of ice crystals |
| cumulus | fluffy white clouds with darker bases |
| cumulus | look like cotton balls |
| cumulus | if they continue to grow taller, they can produce a brief shower |
| cumulonimbus | talles clouds and are called thunderheads, can produce heavy rainfall |
| stratus | causes the sky to look gray |
| stratus | produce steady light precipitation |
| fog | a cloud that rests on the ground or body of water |
| fog | a thick mist formed by water vapor in the air condenses as it cools |
| precipitation | forms from water droplets or ice crystals |
| precipitation | comes from clouds |
| precipitation | formed through the combining of cloud droplets |
| precipitation | form through the growth of ice crystals |
| rain guage | used to measure precipitation |
| long ruler | used to measure snow depth |
| rain or drizzle | most common type of precipitation |
| raindrops | form from liquid cloud droplets or from ice crystals taht melt as they fall |
| drizzle | a light rain with very small drops |
| drizzle | usually comes from stratus clouds |
| freezing rain | raindrops frozen when they hit the ground or other surface |
| freezing rain | covers surfaces with a coating of ice |
| sleet | small pellets of ice that form when rain passes through a layer of cold air |
| snowflake | have six sides or branches |
| snow | formed as ice crystals grow and merge in clouds |
| hail | largest type of frozen precipitation and ofen occurs in warm weather |
| hail | lumps or balls of ice that fall from cumulonimbus clouds |
| acid rain | rain that becomes more acidic than normal because of pollution |
| acid rain | caused by factories, automobiles, natural sources of released sulfur dioxide and nitrogen oxides |
| air pressure | decreases as you move higher in the atmosphere |
| winds | blow from areas of high pressure toward areas of low pressure |
| Earht's rotation | causes long distances wind to bend or curve |
