FORMATION OF THE ATMOSPHERE

Atmosphere -gases that surround the Earth.

Earth’s 1st Atmosphere 4.6 billion years ago

Made of Hydrogen (H) & Helium (He).

Earth’s 1st Atmosphere 4.6 billion year ago

These light gasses (H & He), were heated by solar radiation and escaped the gravitational pull of earth.

The gasses were carried away by the solar wind.

FYI: Venus and Mars also had the same

1st atmosphere of H & He.

Earth’s 2nd atmosphere Volcanic eruptions all over earth produced

water vapor, carbon dioxide, & nitrogen gas.

Earth’s 2nd atmosphere

The only living organisms were bacteria and microorganisms.

100’s of millions of years passed

Earth’s 2nd atmosphere

The earth continued to cool & water vapor formed clouds.

Rain fall formed the oceans. Some astronomers also believe our water

came from comets.

Earth’s third atmosphere (Our Current Atmosphere)

Oxygen appeared when energy from the sun broke the water vapor H2O into H & 0.

Earth’s third atmosphere (Our Current Atmosphere)

However, most of the

oxygen came from photosynthesis, when plants appeared 2-3 billion years ago.

Photosynthesis makes

oxygen by turning H20 and CO2 into organic matter.

As plants became wide spread oxygen became abundant in the atmosphere.

Today our atmosphere is: • 78% Nitrogen (N2) • 20.95% Oxygen (O2) • 0.93% Argon (Ar) • 0.038% Carbon Dioxide (CO2) • trace amounts of Other gases (ex: H2O )

Earth’s third atmosphere (Our Current Atmosphere)

Earth’s Atmospheric Gasses

Layers of the Atmosphere

Key Concepts

Order of the Layers

1. Troposphere 2. Stratosphere 3. Mesosphere 4. Thermosphere

Troposphere The layer of the atmosphere where weather occurs

Stratosphere The layer of the atmosphere that contains ozone

Mesosphere The layer of the atmosphere where most meteoroids burn up

Thermosphere The hottest layer of the atmosphere that’s divided into two parts

Ionosphere Thermosphere layer that bounces radio waves

Exosphere Outermost layer of the thermosphere