Chemistry of the Atmosphere

Atmosphere

Gaseous envelope surrounding
the Earth

Atmos

Greek: Vapor/Steam

Sphaira

Greek: Ball/Globe

Atmosphaera

Modern Latin

Layers of Atmosphere

Troposphere

Stratosphere

Mesosphere

Thermosphere (Ionosphere)

Exosphere

Troposphere

Closest to Earth’s surface (7-18 km above the equator).

Troposphere

Most active region – where all the dramatic events of weather (rain, lightning, hurricanes) occur.

Troposphere

Contains almost 80% of the total mass of air and practically all the atmosphere’s water vapor (forms clouds and rain).

Troposphere

Thinnest layer of the atmosphere (10 km).

Troposphere

Temperature decreases with increasing altitude.

Stratosphere

Consists of nitrogen, oxygen and ozone.

Stratosphere

19-50 km above the equator.

Stratosphere

Air temperature increases with altitude due to the exothermic reactions triggered by UV radiation from the sun.

Stratosphere

One of the products of this reaction sequence is ozone (O3), which serves to prevent harmful UV rays from reaching Earth’s surface.

Mesosphere

30-50 km above the equator.

Mesosphere

The concentration of ozone and other gases is low.

Mesosphere

The temperature decreases again with increasing altitude.

Thermosphere (Ionosphere)

50-400 km above the equator.

Thermosphere (Ionosphere)

Temperature increases with altitude – as the result of the bombardment of molecular O2 and N2 and atomic species by energetic particles, such as electrons and protons, from the sun.

Thermosphere (Ionosphere)

In reverse, these processes liberate the equivalent amount of energy, mostly heat.

Thermosphere (Ionosphere)

Ionized particles are responsible for the reflection of radio waves back toward Earth.

Exosphere

~400 km above the equator.

Exosphere

The outermost layer of our atmosphere.

Exosphere

This layer separates the rest of the
atmosphere from outer space – 10,000 km
thick.

Exosphere

There is a lot of empty space in between of
very spread out hydrogen and helium gases.

Exosphere

There is no air to breathe and it is very cold.

Atmosphere

The total mass of the atmosphere is about 5.3 x 10^18 kg.

Atmosphere

Water is excluded from this table because its concentration in air can vary drastically from location to location.

Nitrogen Cycle

Molecular nitrogen, with its triple bond, is a very stable molecule.

Nitrogen Fixation

the conversion of molecular nitrogen into
nitrogen compounds such as nitrates.

Nitric Acid

is converted to nitrate salts in
the soil.

Oxygen Cycle

The cycle is complicated because oxygen takes so many different chemical forms.

Oxygen Cycle

Atmospheric oxygen is removed through respiration and various industrial processes (mostly combustion), which produces CO2.

Photosynthesis

is the major mechanism by which molecular oxygen is regenerated from CO2 and water.

Aurora

Spectacular celestial light shows as a result of ejection of myriad electrons and protons in space during solar flares or violent eruptions on the surface of the sun.

Aurora Borealis

Northern Hemisphere

Aurora Australis

Southern Hemisphere

Aurora

These electrons and protons collide with the molecules and atoms in Earth’s upper atmosphere, causing them to ionized and electronically excited.

excited molecules, ions

The ____ and ____ return to the ground state with the emission of light.

Excited Oxygen

atom emits photons at wavelengths of 558 nm (green) and between 630 and 636 nm (red).