Earth’s atmosphere Earth’s atmosphere is a thin layer of gases. It is unique in its composition and temperature so life can exist on Earth

Makeup of atmosphere The atmosphere is made of : solids (salt, pollen, dust) liquids (water, volcanic acids) gases (nitrogen, oxygen, argon, carbon dioxide, water vapor)

The Early Atmosphere Earth's first atmosphere 4.6 billion years ago was most likely comprised of hydrogen and helium (two most abundant gases found in the universe!) The first atmosphere had no oxygen. Oxygen was produced by early organisms (cyannobacteria) and later by green plants.

Through the process of outgassing, the outpouring of gases from the earth's interior, many other gases were injected into the atmosphere. These include: water vapor (produced rain - rivers, lakes, oceans) carbon dioxide nitrogen As outgassing occurred over a period of millions of years, the atmosphere changed to its current state

Layers of the atmosphere 5 layers: –Troposphere (weather, decrease temp) –Stratosphere (ozone, increase temp) –Mesosphere (meteors, decrease temp) Ionosphere within mesosphere & thermosphere –Thermosphere (thick, high temp) –Exosphere (shuttle orbit, high temp)

Atmospheric Pressure Air pressure decreases as you go higher in Earth’s atmosphere. This is due to fewer molecules at high altitudes. Jet cabins must be pressurized & people have difficulty breathing in high mountains.

The ozone layer Ozone absorbs most of the sun’s harmful UV radiation. It is made of 3 oxygen atoms bonded together ( O 3 ) CFCs are destroying the ozone The ozone hole is over Antarctica in December.

Energy transfer in the atmosphere Conduction – energy transfer when molecules collide Radiation – energy transfer by rays or waves Convection – energy transfer by flow of material

The water cycle Hydrosphere – water portion of Earth 3 major processes: Evaporation (Sun’s energy moves vapor into atmosphere) Condensation (Cloud formation) Precipitation (Water returns to Earth’s surface)

What happens to the sun’s energy that reaches Earth? Reflection –6% by atmosphere –25% by clouds –4% by Earth’s surface Absorption –15% by atmosphere –50% by Earth’s surface

Formation of Wind Areas of Earth receive different amounts of solar radiation. This is due to Earth’s curved surface. Areas near the equator receive more direct rays from the sun. Areas near the poles receive slanted rays from the sun.

Formation of Wind Cold, dense air at the poles sinks and moves along Earth’s surface. This forces warm, less dense air near the equator to rise.

Formation of Wind Cold, dense air has HIGH pressure. Warm, less dense air has LOW pressure. Winds form as air moves from areas of HIGH to areas of LOW pressure H → L

The Coriolis Effect The Coriolis Effect causes moving air (and water) to turn to the right in the Northern hemisphere and to the left in the Southern hemisphere.

Wind Due to uneven heating of Earth’s surface and the Coriolis effect, winds have distinct patterns on Earth’s surface. Winds are named for the direction from which they blow.

Jet Streams Narrow belts of wind that blow near the top of the troposphere. Jet streams form at the boundary between cold, dry polar air and warm, moist tropical air. Jet streams are faster in winter. Jet streams are seasonally at different locations. Jet streams move storms / weather from West to East

Jet Streams Flying from Boston to Seattle may take 30 minutes longer than flying from Seattle to Boston. WHY?

Land and Sea Breezes During the day, cool air from the water moves over the land, creating a sea breeze. At night, cool air over the land moves toward the warmer air over the water, creating a land breeze. These daily winds occur because land heats and cools faster than water.

Sea & Land Breezes

Mountain and Valley Breezes System of winds that blow downhill during the night and uphill during the day.