Weather World Geography Notes 1.5

Atmosphere Atmosphere is a thin layer of gases This protects the surface from Temperature extremes (acts as insulation) Space debris Dangerous radiation Gravity holds Earth’s atmosphere

Nearly all atmospheric gases are contained within around 20 miles of Earth Weather occurs within 10 miles

Composition Oxygen and Nitrogen make up 99% of dry air This excludes water vapor Nitrogen comprises 78% of the atmosphere Oxygen comprises 21% of the atmosphere Vital to respiration Active 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 vapor Carbon 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 atmosphere Carbon dioxide levels decrease in the summer when plants turn it to oxygen and carbon Carbon dioxide and other gases play an important part in the greenhouse effect Which heats the Earth

In addition to gases, Earth’s atmosphere also contains aerosols and particulates. From natural and industrial processes Light enough to stay suspended in the air Can 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

Pollution These aerosols, particulates, and atmospheric gases become pollutants when: Their concentrations increase to levels that threaten the health of living things Substantially change existing atmospheric conditions

Earth’s Radiation Balance Earth 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 Radiation There are different types of radiation that are identified by their wave length The distance between wave crests Visible light ranges in wavelength 0.4 microns to 0.7 microns

Insolation Insolation is a stream of radiant energy Only 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 or Absorbed 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