Class Outline

• What is Radiation and Radiative Forcing?– How does radiation differ from convection and conduction?

• How does radiation from the sun interact with the Earth?• How does radiation from the Earth interact with

greenhouse gases?– What is absorption, reflection and transmittance?

• How are greenhouse gas amounts changing?• How can we observe the radiation that leaves the earth

from satellites?– What does this information tell us about the temperature of

features on Earth?

What is radiation?

DEMO TIME!

FAQ 1.1, Figure 1

Earth’s energy balance

Green-house effect

What wavelengths of light does the sun emit?

or

A quick description of the sun’s energy

RadioMicrowavesInfraredVisible UltravioletX RaysGamma Rays

Wavelengths of LightW

avel

engt

h In

crea

ses

Light: Color and Wavelength

Distance (nanometers: millionths of a millimeter)

Violet (400 nm)

Indigo (425 nm)

Blue (450 nm)

Green (525 nm)

Yellow (575 nm)

Orange (615 nm)

Red (700 nm)

Light emitted by the Sun

http://feps.as.arizona.edu/outreach/bbplot.html

Wavelength of Peak emission = 2898 microns / Temperature of Blackbody (Kelvin).

Sun and Earth Energy Emission

http://ceos.cnes.fr:8100/cdrom-00b/ceos1/science/dg/dg9.htm

What kind of light does the sun emit?

DEMO TIME!

What is radiative forcing?

• Radiative forcing is a measure of the influence that a factor has in altering the balance of incoming and outgoing energy in the Earth-atmosphere system.

• Radiative forcing is an index of the importance of the factor as a potential climate change mechanism.

FAQ 1.1, Figure 1

Earth’s energy balance

Green-house effect

Earth’s Energy Balance

• Over the long term, the amount of incoming solar radiation absorbed by the Earth and atmosphere is balanced by the Earth and atmosphere releasing the same amount of outgoing longwave radiation.

• About half of the incoming solar radiation is absorbed by the Earth’s surface. – This energy is transferred to the atmosphere by

• warming the air in contact with the surface (thermals), • evapotranspiration • longwave radiation that is absorbed by clouds and greenhouse

gases.

– The atmosphere in turn radiates longwave energy back to Earth as well as out to space.

Greenhouse Gases

Global Carbon DioxideN

AS

A

Changes in Greenhouse Gases

The global increases in carbon dioxide concentration are due primarily to fossil fuel use and land-use change.

Changes in Greenhouse Gases

The increases of methane and nitrous oxide are primarily due to agriculture.

Reflection, transmittance and absorption

Absorption

DEMO TIME!

• Global Warming Art

• http://www.globalwarmingart.com/wiki/Image:Atmospheric_Transmission_png

Why different bands for water?

• The water vapor absorption bands are related to molecular vibrations involving different combinations of the water molecule’s three fundamental vibrational transitions:– symmetric stretch mode – bending mode – asymmetric stretch mode

Water Vapor Molecule Animation

• http://en.wikipedia.org/wiki/Water_absorption

How do we observe Earth’s radiation that goes to space?

Satellites

• Monitor one area constantly, as it remains stationary with respect to an observer on earth’s surface

Scan from north to south

Visible Light

Infrared Light

What will we study using satellite imagery of clouds and water

vapor?

•Thickness of clouds•Height of Clouds•Amounts of Water Vapor•In the next couple weeks we will discuss overall climate effects of clouds

How is our atmosphere structured?

Atmospheric Vertical Structure

Photo Credit: Bob Rohli

What do clouds look like from Earth above and below?

Name that Cloud!

STRATOCUMULUSStable layers in the atmosphere slow vertical

development. Rounded masses larger than altocumulus. Often appear near sunset as the spreading remains of larger cumulus clouds.

Name that Cloud!

STRATUSA uniform grayish cloud that often covers the entire sky. Resembles fog that does not reach

the ground. Layer of air cooled to the saturation point. Featureless with ill defined

top and bottom.

Name that Cloud!

ALTOCUMULUSForms in unstable layer bounded by an upper

stable layer. Possible marker of PM t-storms when seen in the AM with greater vertical

development. Gray, puffy masses.

Name that Cloud!

NIMBOSTRATUSA clouds producing continuous precipitation (light to moderate). Thick mass of cloud with

no well defined base, dark gray in color, usually covering most of the sky.

Name that Cloud!

CUMULONIMBUSOr “thunderstorm” cloud. Most energetic of cumulus family. Top can shoot up into lower stratosphere. Anvil cloud is forming. Heavy downpours, lightning, and hail can result.

Name that Cloud!

CIRROCUMULUSSmall ripples strongly resemble the scales of a

fish. Usually occur in patches and do not cover entire sky. Heaps smaller than

altocumulus.

Common Cloud Types

Click here for:

Satellite loop of the United States

Are the clouds moving in your direction?

When will they reach you?

Earth Surface

Infrared Energy

Infrared Energy

High CloudHigh Cloud

Low CloudLow Cloud

Cold

Satellite

Infrared Image

Warm

Appears Gray Appears White

High and Low Clouds in Infrared Image

Visible image Infrared image

Click here for:

Infrared Satellite loop of the United States

Are the clouds moving in your direction?

When will they reach you?