15.3 ENERGY IN THE ATMOSPHERE

The Water Cycle Continues

Learning Targets

1. Describe how energy is transmitted2. Describe the Earth’s heat budget and

what happens to the Sun’s energy3. Discuss the importance of convection

in the atmosphere4. Describe how a planet’s heat budget

can be balanced5. Describe the greenhouse effect and

why it is so important for life on Earth

Energy

1. All matter has energya) All atoms are in constant motion

2. Law of Conservation of Energya) Energy cannot be created or destroyedb) Examples: photosynthesis (solar

chemical)

3. Many formsa) Light, heat, motion, electrical,

nuclear, etc.

Transfer of Heat Energy

1. Through mattera) Conduction – contact in solidsb) Convection – movement of heated

particles in fluids

2. Radiationa) Through empty space

i. Electromagnetic waves

Radiant Energy

1. Radiationa) Ultraviolet (UV)

i. High energy, damages DNA, shorter wavelength

ii. Source: Sun, specialty lights

b) Visiblei. Energy we detect as light and colorii. Source: Sun, flashlight, candle

c) Infraredi. Low energy, felt as heat, longer

wavelengthii. Source: all matter above absolute zero

Solar Energy That Reaches Earth’s Surface

1. Ultravioleta) ~7%b) UVA, UVB, UVC

i. All UVC blocked by ozone

c) 99% of UV blocked by ozone layer

2. Visiblea) ~44%

3. Infrareda) ~49%b) Solar heat

Solar Energy

1. What are some objects that appear to radiate visible light, but actually do not?

2. Reflection – When light (or another wave type) bounces back from a surface

3. Albedo – Measure of how well a surface reflects light (another wave type)

Temperature vs. Heat

1. Temperature is a measure of how fast the atoms in a material are vibrating

2. Heat is taken in or released when an object changes state of matter

a) Measures the material’s total energy

3. As temperature increases, the molecules vibrate faster, which generates heat.

Heat in the Atmosphere

1. Moves mostly by convectiona) Weather and windb) It’s all about warm and cold

water

2. Controlled by watera) Latent heat

i. Absorbs/releases heat during phase changes

b) High specific heat

Latent Heat

Specific Heat

1. The amount of energy needed to raise the temperature of one gram of material by 1.00 C.

2. Water vs. Asphalt

Solar Radiation on Earth

1. Insolation – differences in the amount of solar radiation that reaches a given area in a given time

a) Cause winds, affect climate, drive ocean currents

2. Solar radiation unevenly distributed

Seasons

1. Caused by tilt of the earth on its axis

2. Winter solar energya) Less directb) Fewer hours each day

3. More on this in other units

Earth’s Heat Budget

1. Absorb vs. Albedo2. Albedo: measure of how well a

surface reflects light (Reflection of Solar Energy)

a)Low albedo: dark soil or rockb)High albedo: fresh snow

3. One exception: The Greenhouse Effect

Greenhouse Effect

1. Warms troposphere2. Infrared heat is reflected back to the

surfacea) Don’t confuse with o-zone; UV reflects out to

space

3. Natural processa) May be affected by humans

4. Greenhouse gasesa) Methane, carbon dioxide, water vapor,

CFCs