Layers & Composition of the Atmosphere

• Quiz Review Study Guide

Layers of the Atmosphere

• The layers of the atmosphere include troposphere, stratosphere, mesosphere, thermosphere, and exosphere.

Troposphere

• It is the lowest layer of the atmosphere.
• All weather takes place in the troposphere along with the clouds.
• As altitude increases, temperature decreases.

Stratosphere

• The stratosphere is the second highest layer of the atmosphere.
• Ozone absorbs ultraviolet radiation from the sun.
• Temperature increases as altitude increases.

Mesosphere

• The mesosphere is the third highest layer of the atmosphere.
• Meteoroids burn up in the mesosphere.
• Temperature decreases as altitude increases.

Thermosphere

• The thermosphere is the uppermost layer of the atmosphere.
• It is the least dense layer.
• Temperature increases as altitude increases.

Exosphere

• The exosphere is the outermost layer, the layer in space.

Composition of Atmosphere

• The atmosphere consists of 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide, 0.0018% neon, 0.0005% helium, 0.0001% krypton, and 0.000009% xenon.

Condensation

• Condensation is the change of state from a gas to a liquid.
• Water vapor condenses into water droplets.
• A drop in temperature can cause condensation.
• Condensation causes the formation of clouds and fog.

Dew Point

• Dew point is the temperature at which the rate of condensation equals the rate of evaporation.
• Clouds and fog form when the temperature is at or below the dew point.

Cloud Formation

• Clouds form when water vapor turns back into liquid water droplets.

Why Clouds are White

• Clouds appear white because their water droplets or ice crystals are large enough to scatter the light of the seven wavelengths.

Why Clouds Turn Gray

• Clouds turn gray when they are made up of tiny water droplets or ice crystals, making the clouds appear white.
• Clouds appear gray or dark when thick or high enough that all the light above does not make it through.
• Cloud shadows can add to the gray or multicolored gray appearance.

Orographic Lifting

• Air is forced over a barrier such as a mountain causing a rain shadow.

Convective Lifting

• Air lifting is due to local surface heating.
• The surface is heated from the sun's radiation causing the air to warm and rise.
• This causes rain and thunderstorms.

Convergent Lifting

• Air flows toward areas of low pressure, forcing air to rise.
• This process causes thunderstorms.
• Convergent lifting occurs when two air masses collide, forcing some air upward since both air masses cannot occupy the same space.

Frontal Lifting

• Frontal lifting occurs along boundaries of different air masses namely cold and warm fronts.
• Cool air is denser than warm air.
• Cool air sinks down and warm air rises
• This creates different types of weather.

Low Level Clouds

• Stratus clouds are among the low-lying clouds, and are typically gray clouds that cover the entire sky.
• They can be the result of very thick fog lifting in the morning..
• Nimbostratus clouds are dark gray clouds that produce falling rain or snow.

Mid-Level Clouds

• Cumulus clouds are composed of water droplets and are typically gray and puffy.
• These clouds are commonly seen on warm and humid summer mornings and often indicate that thunderstorms will follow later in the day.

High Level Clouds

• Cirrus clouds are thin and wispy clouds that are blown by high winds.
• They indicate the day will have fair or pleasant weather.
• The direction of cirrus clouds shows the direction that the air moves at their altitude.

Vertical Clouds

• Cumulonimbus clouds bring lightning, thunder, violent tornadoes, and other intense weather situations.

Fog

• Fog is a cloud that touches the ground.

Elements of Weather

• The elements of weather are temperature, pressure, wind, humidity, clouds, and precipitation.

High Pressure System

• A high pressure system is a dense air mass that is usually cooler and drier than the surrounding air.

Low Pressure System

• A low pressure system is a less dense air mass that usually brings in precipitation and is warmer than the surrounding air.

Cold Front

• A cold front is the transition area where a mass of cold air moves in to replace a mass of warm air.

Warm Front

• A warm front is the transition area where a mass of warm air moves to replace a mass of cold air.

Stationary Front

• A stationary front occurs when a cold front and a warm front meet up but neither moves out of the way.
• Stationary fronts bring long rainy periods that stay in one spot.

Occluded Front

• Occluded front occurs when cold fronts move faster than warm fronts, resulting in a cold front catching up to a warm front