Weather World Geography Notes 1.5. Atmosphere Atmosphere is a thin layer of gases This protects the surface from Temperature extremes (acts as insulation)

WeatherWorld Geography Notes 1.5

AtmosphereAtmosphere is a thin layer of gases

This protects the surface from Temperature extremes (acts as insulation)Space debrisDangerous radiation

Gravity holds Earth’s atmosphere

Nearly all atmospheric gases are contained within around 20 miles of Earth

Weather occurs within 10 miles

CompositionOxygen and Nitrogen make up 99% of dry air

This excludes water vapor

Nitrogen comprises 78% of the atmosphere

Oxygen comprises 21% of the atmosphereVital to respirationActive agent in weathering

Weather and climate are not affected much by nitrogen or oxygen.

The variable gases that are most important to weather and climate are:Water vaporCarbon dioxide

Water vapor is the most variable: May make up .1% to 4% of the lower atmosphere’s

volume

It is affected by: Exposed surface water Atmospheric temperature Altitude

Water vapor is critical in: The process of condensation and precipitation Transporting heat around the world through latent

heating

Carbon dioxide is the other very important gas in weather and climate.On average makes up .035% of the atmosphereCarbon dioxide levels decrease in the summer

when plants turn it to oxygen and carbonCarbon dioxide and other gases play an important

part in the greenhouse effectWhich heats the Earth

In addition to gases, Earth’s atmosphere also contains aerosols and particulates.From natural and industrial processesLight enough to stay suspended in the airCan significantly affect weather and climate

Can reduce the amount of energy Earth receives from the sun Can lead to short term global cooling

Also can act as nuclei for condensation of cloud droplets

PollutionThese aerosols, particulates, and atmospheric

gases become pollutants when:Their concentrations increase to levels that threaten

the health of living thingsSubstantially change existing atmospheric conditions

Earth’s Radiation BalanceEarth maintains a radiation balance:

Energy coming from the sun must eventually be equaled by energy radiated and reflected from Earth.

This process helps explain weather patterns

Solar RadiationThere are different types of radiation that are

identified by their wave lengthThe distance between wave crests

Visible light ranges in wavelength 0.4 microns to 0.7 microns

InsolationInsolation is a stream of radiant energyOnly about 52% passes through the atmosphere to

reach Earth’s surface. The atmosphere: absorbs (~23%), reflects (~17%), and

scatters (~8%)

Reflection of insolation is determined by an objects albedo (reflectivity)

On average about 52% of insolation reaches Earth’s surface where it is:Reflected orAbsorbed and converted to kinetic energy

This creates and moves weather

Albedo can range from 3% to 95%Water has an albedo of 3% to 10%, but has a higher

albedo as it approaches the poles (nearly 100% in some cases)

Global Radiation Balance

Heat and Temperature

Greenhouse Effect

Vertical Temperature Change

Diurnal and Seasonal Temperature Patterns

Spatial Temperature Patterns

Temperature and Humans

Atmospheric Pressure and Winds

Atmospheric Pressure

Altimeters

Pressure Variations

Patterns of Atmospheric Pressure

Wind

Wind Speed

Local and Regional Winds

Monsoons

Global Winds and Ocean Currents

Weather Systems