Study Guide for Apologia Physical Science Module 14

Atmosphere

The mass of air surrounding a planet, such as Earth.

Atmospheric Pressure

The pressure exerted by the atmosphere on all objects within it. At sea level, it's approximately 14.7 pounds per square inch (psi) or 760 millimeters of mercury (mmHg).

Barometer

An instrument used to measure atmospheric pressure.

Homosphere

The lower layer of Earth's atmosphere, extending from ground level to about 80 kilometers (50 miles) above sea level, where the composition of gases is relatively uniform.

Heterosphere

The upper layer of Earth's atmosphere, above the homosphere, where gases are layered by atomic mass.

Troposphere

Extends from the Earth's surface to about 11 kilometers (7 miles). Weather phenomena occur here.

Stratosphere

From approximately 11 km to 48 km (7 to 30 miles). Contains the ozone layer, which absorbs and scatters ultraviolet solar radiation.

Mesosphere

From about 48 km to 80 km (30 to 50 miles). Meteors burn up in this layer.

Thermosphere

From roughly 80 km to 460 km (50 to 286 miles). Solar radiation causes ionization of atoms, leading to auroras.

Exosphere

Above 460 km (286 miles). The outermost layer where atmospheric particles are extremely sparse.

Temperature

A measure of the average kinetic energy of the particles in a substance.

Heat

The energy transferred between substances due to a temperature difference.

Kinetic Theory of Matter

States that all matter is composed of tiny particles in constant motion. The temperature of a substance depends on the average kinetic energy of its particles.

Latent Heat

The heat required to change the state of a substance without changing its temperature.

Pressure

The force exerted per unit area. Atmospheric pressure is the weight of the air above us.

Wind

Air in motion relative to the Earth's surface. Wind is caused by the uneven heating of the Earth's surface, leading to differences in air pressure.

Jet Streams

Narrow bands of high-speed winds found in the upper levels of the atmosphere.

Greenhouse Effect

Certain gases in Earth's atmosphere, such as carbon dioxide and methane, trap heat, preventing it from escaping into space.