Visualizing Environmental Science

PROCESS DIAGRAM

many kinds of organisms on Earth are here in part be-
cause of the large number of different climates—from
cold, snow-covered polar climates to tropical climates
that are hot and have rain almost every day (ˆ}ÕÀiʙ°£).

Solar Radiation and Climate

The sun makes life on Earth possible. Sunshine, or in-
solation, warms the planet, including the atmosphere,
to habitable temperatures. Without the sun’s energy, all
water on Earth would be frozen, including the ocean.

Photosynthetic organisms capture the sun’s energy and

use it to make the food molecules almost all forms of life

require. Most of our fuels, such as wood and fossil fuels

(oil, coal, and natural gas), originated as solar energy cap-

tured by photosynthetic organisms. The amount of insola-

tion that reaches Earth is a key factor in the overall climate.

The uneven distribution of the total insulation around the

globe is a major determinant of regional climates.

Clouds, and to a lesser extent snow, ice, and the ocean,

reflect away about 31 percent of the solar radiation that

falls on Earth (ˆ}ÊÕÀiʙ°Ó). The remaining 69 percent is

>ÌiʜvÊ܏>ÀÊÀ>`ˆ>̈œ˜Ê̅>ÌÊÀi>V…iÃÊ

>À̅ÊUʈ}ÕÀiʙ°Ó

Most of the energy that the sun produces never reaches Earth. The solar energy that reaches Earth

warms the planet’s surface, drives the hydrologic cycle and other biogeochemical cycles, produces our

climate, and powers almost all life through photosynthesis. On average, about 1366 watts per square

meter (W/m^2 ) enter Earth’s atmosphere, resulting in about 1000 W/m^2 at Earth’s surface.

✓✓THE PLANNER

Total reflection

back into space

31%

Entering solar radiation

(insolation)

100%

Total absorption by

atmosphere, land, and water

69%

Reflection by

particles in

atmosphere

3%

Reflection off

ice, snow, and

light-colored land

9%

Reflection by

clouds in

atmosphere

19%

Absorption by

gases and particles

in the atmosphere

17%

Absorption

by clouds

3%

Absorption

by land

and ocean

heats Earth

Warmed surface re-emits 49%

heat as infrared radiation,

which is returned to

space or to surface (by

greenhouse gases).

The Atmosphere and Climate 219

Ice is highly reflective compared to water and

land. How will this diagram change as ice caps and glaciers melt?

Think Critically