Earth's Atmosphere

Properties of Air

Air is a mixture of gaseous elements and compounds, such as:

  • Nitrogen (most abundant)

  • Oxygen (second most abundant)

  • Water vapor

  • Argon

  • Carbon dioxide

Air pressure: the pressure that air exerts on us

  • Decreases as altitude increases

Humidity: the amount of moisture in the air

  • When it rains, the humidity is 100% because the clouds are unable to hold more water

Temperature: the amount of thermal energy in the air

These three properties of the atmosphere help to determine the weather conditions.

Clouds are important indicators of atmospheric conditions. Four major types of clouds are:

  • Cumulus clouds: fluffy and white with flat bottoms; indicate fair weather

  • Cumulonimbus clouds: produce thunderstorms; are made when cumulus clouds become larger and darker

  • Stratus clouds: smooth, gray clouds that cover the whole sky; associated with light rain

  • Cirrus clouds: feathery; associated with fair weather, but often indicate that rain or snow will fall within several hours

Atmospheric Layers

The atmosphere is made up of layers, which are, in order from lowest to highest:


  • The location where most weather takes place and where most clouds are

  • Air pressure and temperature decrease as you climb higher in this layer


  • Is the location of the ozone layer, which protects us from the sun’s ultraviolet (UV) rays

  • Since weather mostly doesn’t occur in this layer, planes fly in the lower stratosphere to avoid turbulence


  • Meteors burn up in this layer

  • Some of the coldest temperatures in Earth’s atmosphere are found here


  • This layer is very hot because it absorbs high energy radiation from the Sun


  • The outermost layer that some consider to be a part of outer space

  • The air in this layer is very thin

Effect of Human Activity

Global Warming

Global warming/climate change: the warming of Earth’s surface due to human activities

Effects of global warming:

  • Rising sea levels

  • Shrinking glaciers

  • Faster melting in the Arctic and Antarctica

  • Changes in flower and plant blooming times

Greenhouse effect: gases in the atmosphere such as carbon dioxide and methane prevent heat from escaping, making the Earth’s surface warmer

Humans release greenhouse gases through burning fossil fuels in factories and vehicles.

Ozone Layer

The Sun’s harmful ultraviolet (UV) rays have negative effects, such as:

  • Skin cancer

  • Cataracts (an eye problem)

  • Harm to crops

  • Harm to marine life

The ozone layer protects us from the effects of UV rays. Ozone is a form of oxygen. However, human activity and the chemicals we release into the atmosphere is breaking down the ozone layer.

Maintaining good air quality is a crucial goal for modern society, and it is everyone’s responsibility to work toward it.

Weather Maps

Weather maps are important for understanding and predicting the weather.

High pressure system: whirling mass of cool, dry air that brings good weather and sunny skies; represented by an 'H'

Low pressure system: whirling mass of warm, moist air that brings stormy weather and wind; represented by an 'L'

Air mass: large body of air that has similar properties throughout

Front: a boundary between two different air masses, resulting in stormy weather

Types of fronts:

  • Cold front: a boundary between a cold and warm air mass in which the cold air is replacing the warm air

  • Warm front: a boundary between a cold and warm air mass in which the warm air is replacing the cold air

  • Stationary front: a boundary between two air masses that doesn’t move


Sources Used and Helpful Links