science test on atmosphere flash cards

Atmosphere

The layer of gases surrounding the Earth, held near its surface by gravity.

Three states of matter in Earth's atmosphere

1. Gas: Nitrogen, oxygen, carbon dioxide
2. Liquid: Water droplets in clouds
3. Solid: Dust, pollen, and ice crystals

Two most abundant gases in Earth's atmosphere

Nitrogen ($78\%$) and oxygen ($21\%$).

Weather

The condition of Earth's atmosphere at a particular time and place, including temperature, wind, clouds, precipitation, and air pressure.

Water vapor

Invisible water in its gaseous state formed when liquid water evaporates.

Distinction between water vapor and steam

Water vapor is invisible gas; steam in everyday language refers to the visible mist of tiny liquid water droplets that forms as hot water vapor cools.

Composition of clouds

Tiny liquid water droplets, ice crystals, or a combination of both.

Reason a cumulus cloud can float despite holding $500,000\,kg$ of water

The water droplets are spread out across a huge volume of air, keeping the overall cloud density low enough to stay aloft.

Density

The amount of mass in a given volume, expressed as $\text{Density} = \frac{\text{Mass}}{\text{Volume}}$.

Effect on density when volume increases while mass stays constant

Density decreases because the same amount of matter is spread over a larger space.

Effect on density when mass decreases while volume stays constant

Density decreases because there is less matter packed into the same amount of space.

Air pressure

The force exerted by moving air molecules as they collide with surfaces, driven by gravity pulling atmospheric air toward Earth.

Two main types of barometers

1. Mercury barometer: Measures atmospheric pressure using a column of liquid mercury.
2. Aneroid barometer: Measures air pressure using a sealed metal chamber that flexes with pressure changes.

Units used to measure air pressure in weather reporting

Millibars (commonly used on weather maps) and inches of mercury (commonly used in US weather reports).

Reason humans are not crushed by atmospheric pressure

The internal pressure inside the human body pushes outward with equal force to balance the external pressure of the atmosphere.

Four main life-sustaining functions of Earth's atmosphere

1. Provides essential gases needed for life (like oxygen and carbon dioxide)
2. Protects Earth from harmful ultraviolet radiation
3. Burns up incoming meteoroids
4. Regulates Earth's temperature

Cause of ear popping at high altitudes or on airplanes

External air pressure drops as elevation increases, creating a pressure difference across the eardrum until the Eustachian tube opens to equalize air pressure in the middle ear.

Effect of high altitude on athletic performance

Lower air pressure reduces air density, meaning each breath provides fewer oxygen molecules, causing muscles to tire faster during physical exertion.

Physiological adaptation gained from high-altitude training

The body adapts to lower oxygen availability by producing more red blood cells and hemoglobin to carry oxygen more efficiently.