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