The Atmosphere

The more than 500 active volcanoes erupting around the world affect the Earth's atmosphere and global climate. As volcanoes erupt, they blast large clouds of gases, particles, water vapor, and aerosols into the atmosphere.

NASA scientists have developed instruments that can make global observations of natural and man-made particles (aerosols) that influence the Earth's climate. They then study the data to help industries, universities, and the public apply their findings to issues ranging from agriculture to city planning.

The Earth is surrounded by a thin envelope of gases called the atmosphere. The atmosphere, or air, contains gases such as oxygen (for breathing), nitrogen, and small amounts of other gases that affect the Earth's climate. Within the Earth's atmosphere, temperatures vary according to the amount of radiant heat received. As a result of the uneven heating of the Earth's atmosphere and surface, the balance between warm and cool air is constantly changing, creating wind.

The air around the Earth is always on the move, both across the surface and up and down in the atmosphere.

Coriolis Effect

• This effect is caused by the rotation of the Earth.
• Winds blow at an angle to the equator (northeast to southeast).
• Winds in the northern hemisphere blow to the right and winds in the southern hemisphere blow to the left.

Trade Winds

• Ground-level winds that flow toward the equator and are deflected by the rotation of the Earth. This deflection is the Coriolis Effect.

Prevailing Westerlies

• Winds that occur between 30 and 60 degrees latitude.
• The air moves towards the poles and appears to curve to the east. Winds originate in the west and travel east.
• These winds are responsible for many of the weather movements across the US and Canada.

Polar Easterlies

• Winds that occur at 60 degrees latitude in both hemispheres.
• The Polar Easterlies are formed when the air over the poles cools and sinks, flowing away from the Earth's poles toward the west.

Jet Stream

• Winds that encircle the Earth in wandering paths, shifting position, and altering speeds.
• Long, narrow, high-speed air currents that flow eastward in a generally horizontal zone in the stratosphere or upper troposphere.
• During the winter, the jet streams are stronger and are positioned nearer to the equator than during the summer.