Topic 5 - Solar Energy, Atmospheric Heating and Global Temperature

What is the Electromagnetic spectrum? (EM spectrum)

Energy that comes from the Sun and other stars. It is made of different   wavelengths of energy.

What part of the EM spectrum can our eyes see?

the visible light

What is a wavelength?

The distance between two wave crests, or two wave troughs, is the wavelength.

Which wavelengths are more damaging to organic material?

short wavelengths

Incoming solar radiation

is considered short wave and consists mostly of visible light, IR and UV radiation

Outgoing thermal radiation

is emitted by Earth itself is in the thermal IR portion of the spectrum and is considered long wave

Which wavelengths are considered less damaging?

long wave

What is Incoming Solar Radiation?

the amount of solar energy that reaches earth’s surface

What does the curvature of Earth have to do with insolation?

Because Earth is curved, the Sun's rays are not evenly received across it. This explains why temperature varies so much across the globe.

When energy reaches earth but it is spread out over a larger area closer to the poles …

When it is spread out, the intensity of the solar rays diminishes/decreases, it gets “diluted”

Why is it so hot between latitudes 23.5 degrees N and S?

Because on a certain day of the year you can be directly under the sun

Insolation at Earth's surface - what patterns do you see?

Insolation is the highest at the subtropical highs – the great world deserts are at these latitudes

What three physical processes help reduce the amount of energy ultimately being received?

scattering, absorption and reflection

What is scattering(aka diffuse radiation)?

Incoming solar rays bounce off of aerosols in the atmosphere

Why does scattering happen?

The rays get scattered and change direction. The energy of the scattered wavelength stays the same        

What is refraction?

As the Sun's rays enter our atmosphere, they pass from one medium to another

What is albedo? What is the relationship to Reflection?

Refers to how reflective a surface is – not necessarily shiny

What does 100% albedo mean?

all light energy is reflected

What does 0% albedo mean?

all light energy is absorbed

What are some examples of high albedo?

white and other light colors, snow and ice

What are some examples of low albedo?

black and dark colors, green vegetation, asphalt

What causes albedo to change?

global warming, seasons, urbanization, deforestation

What is positive feedback ?

because a change continues to occur in response to the input

What is an example of positive feedback?

icefields melting lead to more dark surface showing. This increases absorption, which increases the surface temperature and the cycle continues.

What is absorption?

All insolation that is not scattered or reflected gets absorbed.

How does the sun’s energy get moved around in three ways?

conduction, convection and advection

What is conduction?

Transfer of heat energy from surface-to-surface, or in the air, molecule to molecule. (Direct contact, direct transfer) (ex: coffee mug)

What is convection?

Up and down movement of fluids due to differences in temperature (hot air rises, cold air sinks) (convection goes up and down) Ex: air and water both rise up and sink down

cold air …

sinks

hot air ….

rises

what is advection?

Side to side movement of fluids due to differences in temperature

How is earth directly warmed by solar energy?

Insolation

How is earth indirectly warmed by solar energy?

Reflection of the heat from all sources

Water’s specific heat - What is specific heat?

The amount of energy required to raise 1 g. of water 1⁰ C.