17.2 Heating the Atmosphere

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17.2 Heating the Atmosphere
Energy Transfer as Heat
 Heat is the energy transferred from one object to
another due to the difference in their temperatures
 Electromagnetic Waves
 3 mechanisms of energy transfer as heat:
 Conduction
 Convection
 Radiation
Conduction
 Transfer of heat through matter by molecular activity
 Energy is transferred by the molecules colliding into
each other
 Ex) a hot metal spoon that was left in a hot pan
 Metals are good conductors of heat
 Air is a poor conductor of heat
Convection
 Much of the heat transfer in the atmosphere
 Transfer of heat by mass movement or circulation
within a substance
 Takes place in fluids (ocean and air)
 Takes place in solids (Earth’s mantle)
Radiation
 Travels out in all directions from it source
 Unlike conduction & convection, which need material
to travel through, radiant energy can travel through
the vacuum of space.
 Solar energy reaches Earth by radiation
4 Laws Governing Radiation
 1. all objects, at any temperature, emit radiant energy
 2. Hotter objects radiate more total energy per unit
area than colder objects do
 3. The hottest radiating bodies produce the shortest
wavelengths of maximum radiation
 4. Objects that are good absorbers of radiation are
good emitters as well.
What Happens to Solar Radiation?
 When radiation hits an object 3 different things could
happen:
 Some energy is absorbed by the object
 Substances such as water & air are transparent to
certain wavelengths of radiation
 Some radiation may bounce off the object without
being absorbed or transmitted
Reflection, Scattering, & Absorption
 Reflection: occurs when light bounces off an object.
The reflected radiation has the same intensity as the
incident radiation.
 Scattering: produces a larger number of weaker rays
that travel in different directions. Disperses light
forward & backwards
 Absorption: without the absorbing gases in the
atmosphere, we would not be able to live on Earth due
to the Greenhouse Effect
17.3 Temperature Controls
Why Temperatures Vary
 Factors other than latitude that exert a strong influence on
temperature include heating of land & water, altitude,
geographic position, cloud cover, & ocean currents
 Land heats more quickly & to higher temps. than water. And
land cools quicker than water and to a lower temp.
 Geographic Position
 Altitude
 Cloud Cover & Albedo
World Distribution of Temperature
 Isotherms are lines that connect points that have the
same temperature.
 Study global temperature patterns & the effects of
the controlling factors of temperature

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