Solar radiation from the sun is the primary energy source that drives Earth's climate system.

The troposphere is the lowest layer of the atmosphere and is where most weather occurs.

Evaporation is the process by which water changes from a liquid to a gas.

Oxygen is not a greenhouse gas because it does not absorb infrared radiation.

The average global temperature is approximately 15°C (59°F).

Fog is not a type of precipitation because it does not reach the ground.

Hadley cells are the global wind pattern that circulates air from the tropics to the poles.

Human activity is not a natural factor that affects climate.

Convection is the process by which warm, moist air rises and cools, causing water vapor to condense and form clouds.

Smog is not a type of cloud because it is a mixture of pollutants and fog.

An anemometer is an instrument used to measure wind speed.

A stationary front is not a type of weather front because it does not move.

A front is a boundary between two air masses with different temperatures.

Drought is not a type of severe weather because it is not caused by a sudden change in weather conditions.

Seasons are caused by the Earth's axis tilting away from the sun.