Atmosphere, Weather, and Climate
Domain 7 covers atmospheric structure, weather systems, climate controls, and climate change.
Core rules and concepts
- The atmosphere is mostly nitrogen and oxygen; water vapor, carbon dioxide, and ozone are minor but radiatively important.
- Layers: troposphere (weather), stratosphere (ozone), mesosphere, thermosphere. Temperature trends define the boundaries.
- Pressure decreases with altitude. Winds flow from high to low pressure and are deflected by the Coriolis effect; friction slows surface winds.
- Air masses and fronts: cold fronts are steep and produce short, intense storms; warm fronts are gentle and widespread.
- Cyclones rotate counterclockwise in the Northern Hemisphere; anticyclones sink and clear.
- Climate controls include latitude, altitude, proximity to water, ocean currents, and prevailing winds. Greenhouse gases trap outgoing infrared.
Worked example
Sea-level temperature is 25°C. Using an environmental lapse rate of 6.5°C/km, a mountain at 2 km has T ≈ 25 − (6.5 × 2) = 12°C, before considering moisture and local effects. The lapse rate is an average; inversions can reverse the trend.
Traps that cost marks
Do not confuse weather with climate. The greenhouse effect is not the ozone hole; ozone absorbs ultraviolet, greenhouse gases absorb infrared. Coriolis deflects motion; it does not create wind. High pressure generally means sinking air and fair weather, not storms. El Niño changes patterns; it is not a single storm.