7 The Atmosphere, Weather, and Climate Free Online FlashCards

What are the main gases in dry air?

Dry air is about $78\%$ nitrogen, $21\%$ oxygen, and $0.9\%$ argon; other gases make up much smaller fractions.

Where does nearly all weather develop?

The troposphere is the lowest atmospheric layer. It contains most atmospheric mass and water vapor, and nearly all weather develops there.

How do air pressure and density change with altitude?

Air pressure and density decrease as altitude increases through the atmosphere.

How does the natural greenhouse effect warm Earth?

Greenhouse gases absorb some outgoing infrared radiation and emit infrared energy in all directions, including back toward the surface. This natural greenhouse effect keeps Earth warmer than it would otherwise be.

What does weather describe?

Weather is the short-term state of the atmosphere at a particular place and time, including conditions such as temperature, pressure, humidity, wind, clouds, and precipitation.

How do pressure differences create wind?

Uneven heating creates differences in air temperature and pressure. Air moving from high-pressure areas toward lower-pressure areas creates wind.

How can water vapor become precipitation?

Evaporation adds water vapor to the air. Cooling can condense it into cloud droplets or ice crystals; when these grow heavy enough, they fall as precipitation.

What does climate describe?

Climate is a region’s long-term pattern of weather, commonly described using averages and variations over about $30$ years. It includes precipitation, seasons, winds, and extreme events, not just temperature.

How does Earth’s tilt contribute to seasons?

Earth’s tilted axis changes the angle and duration of sunlight through the year, producing seasons, especially at middle and high latitudes.

What does the ozone layer do in the stratosphere?

The stratosphere’s ozone layer absorbs much of the Sun’s ultraviolet radiation. Temperature generally increases with altitude in this layer.

What happens to sunlight that is not reflected back to space?

Some sunlight is reflected to space by clouds, airborne particles, ice, and bright surfaces. Earth absorbs the rest and emits energy as infrared radiation.

What causes the Coriolis effect?

Earth’s rotation deflects large-scale winds. This deflection is called the Coriolis effect.