The Atmosphere

The Atmosphere

• Weather and Climate• Atmospheric Composition• Atmospheric Structure• Energy, Heat, & Temperature• Review of Earth-Sun Relationships• Incoming Solar Radiation• Atmospheric Heating• What Controls Air Temperature?• World Temperature Distribution

Terms• Weather

– Short-term conditions; change often

• Climate– Long-term composite of weather conditions; changes

more slowly

• Albedo– How reflective a surface is; higher albedo=more

reflective

Terms• Ozone

– O3 molecules; shield Earth from UV rays

• Climate proxy– Way of measuring climate conditions before

records were kept– Ice cores, deep ocean sediments, others

Weather and Climate

PSCI 131: The Atmosphere

Weather and Climate

• Weather: short-term condition; local

• Climate: long-term conditions; regional or global

PSCI 131: The Atmosphere

Weather and Climate

PSCI 131: The Atmosphere

Weather data Climate data

Atmospheric Composition

PSCI 131: The Atmosphere

Major ComponentsPSCI 131: The Atmosphere: Composition

• Don’t vary significantly

Variable ComponentsPSCI 131: The Atmosphere: Composition

• Vary by location and over time

• Three important ones:– Water vapor– Aerosols– Ozone

Variable Components: Water vaporPSCI 131: The Atmosphere: Composition

• Clouds, precipitation

• Greenhouse gas (traps heat)

• State changes absorb or release energy

Variable Components: AerosolsPSCI 131: The Atmosphere: Composition

• Suspended solid or liquid particles

• Dust, pollen, liquid water, bacteria, etc.

• Refract light, give sky its color

Variable Components: OzonePSCI 131: The Atmosphere: Composition

• O3 molecules

• Absorbs UV radiation

• Concentrated in “ozone layer”

Atmospheric Structure

PSCI 131: The Atmosphere

PressurePSCI 131: The Atmosphere: Structure

• Weight of air over a given location

• Decreases with increasing altitude

• 50% of atmosphere’s mass concentrated in lowest 4 miles (out of 90+ miles)

Pressure

PSCI 131: The Atmosphere: Structure

World-record parachutists• Kittinger

– 1960– 19 miles– 614 mph max speed

• Baumgartner– 2012– 24 miles– 843 mph max speed

PSCI 131: The Atmosphere: Structure

Temperature-based StructurePSCI 131: The Atmosphere: Structure

• Four temperature-based layers– Troposphere (lowest)– Stratosphere– Mesosphere– Thermosphere (highest)

Temperature-based Structure

PSCI 131: The Atmosphere: Structure

Energy, Heat, & Temperature

PSCI 131: The Atmosphere

Heat Energy

PSCI 131: The Atmosphere: Energy, Heat, Temperature

• Drives atmospheric activity

• Creates “weather”

• Moves from hotter to cooler

Heat TransferPSCI 131: The Atmosphere: Energy, Heat, Temperature

Earth-Sun Relations (review)

PSCI 131: The Atmosphere

PSCI 131: The Atmosphere: Earth-Sun Relations

PSCI 131: The Atmosphere: Earth-Sun Relations

Incoming Solar Radiation

PSCI 131: The Atmosphere

Incoming Solar Radiation

• Atmosphere can do three things to solar energy:– Reflection

• Albedo: % of incoming energy that is reflected

– Scattering– Absorption

• All three keep energy from reaching surface

PSCI 131: The Atmosphere

PSCI 131: The Atmosphere: Incoming Solar Radiation

100 % Incoming

Absorbed: 50% land/sea, 20% atmosphere

Reflected: 5% land/sea, 20% clouds

Scattered: 5% atmosphere

Atmospheric Heating

PSCI 131: The Atmosphere

The Greenhouse Effect

PSCI 131: The Atmosphere: Atmospheric Heating

1) Short-wavelength (light) energy absorbed by surface. 2) Energy re-radiated at longer wavelengths (heat) by surface. 3) Greenhouse gases absorb heat, re-radiate it again.

What Controls Air Temperature?

PSCI 131: The Atmosphere

Sun Angle

• Sun angle controlled by– Latitude– Season

PSCI 131: The Atmosphere: Controls on Air Temperature

Other Controls on Air Temp

• Geographic location

– Proximity to large bodies of water

– Leeward vs windward side of continent

PSCI 131: The Atmosphere: Controls on Air Temperature

Other Controls on Air Temp

• Geographic location– Proximity to

large bodies of water

PSCI 131: The Atmosphere: Controls on Air Temperature

Other Controls on Air Temp

• Geographic location– Leeward vs

windward

PSCI 131: The Atmosphere: Controls on Air Temperature

Other Controls on Air Temp

• Altitude– Higher = cooler average temps

• Cloudiness

• Ocean currents– Move heat from tropics to colder areas

PSCI 131: The Atmosphere: Controls on Air Temperature

End of Chapter