Ozone Creation

Chapter 4Atmosphere and Surface

Energy Balances

Geosystems 6eAn Introduction to Physical Geography

Robert W. ChristophersonCharles E. Thomsen

Why do we have to learn about energy?

Energy powers the biosphere, hydrosphere, and atmosphere.Energy deficits are created by the earth’s curved surface—solar insolation varies with latitude.To compensate for energy deficits, ocean currents, global winds, and weather systems move energy around the globe. This is why we have weather and climate.

Energy Essentials Energy Pathways and Principles 

Shortwave energy in from the Sun

Longwave energy out from Earth

TransmissionPassage of energy through atmosphere or water

Refers to shortwave radiation that goes straight through the atmosphere to the surface

Energy Pathways

Figure 4.1

Energy PathwaysInsolation input

All radiation received at Earth’s surface – direct and indirect

Scattering (diffuse radiation)

Changing direction of radiation’s movement, without altering its wavelengths

Pollutants, ice, and water vapor increase scattering

Why is diffuse radiation important?Because it colors the sky

Energy PathwaysScattering (diffuse radiation)

Rayleigh Principle – the shorter the wavelength, the greater the scattering; the longer the wavelength, the less the scattering

Shorter wavelengths of visible light (blues and violets) scatter the most and dominate the lower atmosphere

More blue present in sunlight, so the sky is blue

If we had NO atmosphere, what color would the sky be?

Energy PathwaysSunrise/Sunset

When the sun is low on the horizon, its rays must travel through more atmosphere

This increases scattering of shorter wavelengths (blues) so that only the longer wavelengths color the sky (oranges, reds)

Refraction – change in speed and direction of light

When a form of radiation moves from one medium to another (air to water, space to atmosphere), its speed and direction changeThe wavelengths of radiation are bent into different angles, separating the light into its component colorsRainbows – created when visible light passes through raindrops, is refracted, and reflected showing all colors

Energy Pathways

Figure 4.3

Refraction

RefractionMirage – an image that appears near the horizon where light waves are refracted by layers of air at different temperatures and densities on a hot day

When the sun is low in the sky, its light must penetrate through more air – its refracted by layers of air at different temperatures and densities creating a mirage

Refraction

Figure 4.4

Energy EssentialsAlbedo - % of insolation an object reflects

Darker colors have lower albedos (they absorb more insolation)

Lighter colors have higher albedos (they reflect more insolation)

During the day, clouds reflect radiation back to space

At night, clouds reflect longwave radiation back to Earth’s surface

Energy EssentialsAerosols

Volcanic origin

Decrease atmospheric albedos

Leads to cooling of almost 1°F

Insolation reflected by dirty sky

Albedo

Figure 4.5

Energy Balance in the Troposphere  Greenhouse Effect – where gases (carbon dioxide, water vapor, methane, and CFCs) absorb insolation and reradiate it back to Earth in longer wavelengths thereby warming the lower troposphereThe Greenhouse Effect and Atmospheric Warming

Atmosphere absorbs heat energyAtmosphere delays transfer of heat from Earth into space

Earth–Atmosphere Radiation Balance

Figure 4.12

Energy Budget by Latitude

Figure 4.13

Daily Radiation Patterns

Figure 4.14

Simplified Surface Energy BalanceNET R =

+SW (insolation)

–SW (reflection)

+LW (infrared)

–LW (infrared)

Figure 4.16

Global NET R

Figure 4.17

Global NET RNon-vegetated surfaces lose heat in one of 3 ways:

Latent heat of evaporation – energy released as water changes state

Sensible heat – heat you can feel and measure; convection and conduction

Ground heating and cooling – energy stored during warm periods and released during cool periods

Radiation Budgets

Figure 4.20

El Mirage, CA

Pitt Meadows,BC

The Urban Environment

Figure 4.21

Urban Heat Island

Figure 4.22

Urban Heat

IslandPilot

Project

Figure 4.23

Solar Cooking Solution

Figure FS 4.1.1

Solar Energy

Figure FS 4.1.2