What is Energy?
• Energy – the ability to do work
• Everything that is done in the universe requires the
use or transfer of energy.
• Most of the surface processes on Earth are
powered by energy from the Sun.
17.2 Heating the Atmosphere
Energy Transfer as Heat
 Heat is the energy transferred from one
object to another because of a difference in
the objects’ temperature.
 Temperature is a measure of the average
kinetic energy of the individual atoms or
molecules in a substance.
17.2 Heating the Atmosphere
Energy Transfer as Heat
 Electromagnetic Waves
• The sun emits light and heat as well as the
ultraviolet rays that cause a suntan. These forms
of energy are only part of a large array of energy
emitted by the sun, called the electromagnetic
spectrum.
Electromagnetic Radiation(Energy from the
sun)
Electromagnetic Radiation (Energy from
the Sun)
Visible Light Consists
of an Array of Colors
What makes an object hot?
• Heat: form of energy associated
with the motion of atoms or
molecules
• Heat transfer – the movement
of thermal energy due to a
temperature difference(from a
warmer object to a cooler
object)
• When an object is heated, the
particles that make up the
object move faster.
• Heat transfer stops when both
objects reach the same
temperature.
Thermal Energy Transfer
Thermal energy can be transferred by 3 processes:
– Conduction
– Convection
– Radiation
Types of Heat Transfer
• Conduction – heat
movement within an
object or between objects
that are touching.
• Transfer of energy by touch
• Not an effective transfer in
a gas.
• Primarily solids
Conduction
When you heat a metal strip at one end, the heat
travels to the other end.
As you heat the metal, the particles vibrate, these
vibrations make the adjacent particles vibrate, and so on
and so on, the vibrations are passed along the metal and
so is the heat. We call this? Conduction
Types of Heat Transfer
• Convection– heat transfer by
the movement(circulation) in
fluids.
• Caused by density
• Hot fluid rises, cool fluid falls
• Examples:
– air in a heating system
– Generates sea breezes, land
breezes, and surface winds
Fluids are liquids or gases.
Water movement
Cools at the
surface
Cooler
water sinks
Convection
current
Hot water
rises
Air Currents
Why is it windy at the seaside?
Sea Breeze
Sea breeze: During a hot day, the land is
warmer than the sea. Air above the land
is heated and rises up; it is then replaced
by cooler air from the sea
• Occurs during the day
• wind blowing from the ocean towards
land
Land Breeze
Land breeze: During the night, the sea is
warmer than the land because the land
loses its heat much faster than the sea.
Air above the sea is warmer than that
above the land so it rises up to be
replaced by that air above the land.
• Occurs at night
• blows from the land to the water
Sea Breeze
Land Breeze
Heat cells in mantle/asthenosphere
Rising heat cells - plates separate
Sinking heat cells - plates pulled down into mantle
Types of Heat Transfer
Radiation – the movement of
electromagnetic radiation (energy)
through space
• No direct contact between heat
source and an object
• All objects radiate heat: hotter objects
radiate more
• The hotter the object, the shorter the
wavelength
• Radiation can be absorbed or
reflected
• Examples:
--Heat felt from a campfire
--radiation from the sun warms Earth
--energy from the sun’s core heats
outer surface of the sun
17.2 Heating the Atmosphere
What Happens to Solar Radiation?
 Reflection and Scattering
• Reflection occurs when light bounces off an
object. Reflection radiation has the same
intensity as incident radiation.
• Scattering produces a larger number of weaker
rays that travel in different directions.
17.2 Heating the Atmosphere
What Happens to Solar Radiation?
 Absorption
• About 50 percent of the solar energy that strikes
the top of the atmosphere reaches Earth’s
surface and is absorbed.
• The greenhouse effect is the heating of Earth’s
surface and atmosphere from solar radiation
being absorbed and emitted by the atmosphere,
mainly by water vapor and carbon dioxide.
Summary
Summary
Summary
17.3 Temperature Controls
Why Temperatures Vary
 Factors other than latitude that exert a
strong influence on temperature include
heating of land and water, altitude,
geographic position, cloud cover, and
ocean currents.
17.3 Temperature Controls
Why Temperatures Vary
 Land and Water
• Land heats more rapidly and to higher
temperatures than water. Land also cools more
rapidly and to lower temperatures than water.
 Geographic Position
The geographic setting can greatly
influence temperatures experienced at a
specific location
17.3 Temperature Controls
Why Temperatures Vary
 Altitude
• The altitude can greatly influence temperatures
experienced at a specific location.
 Cloud Cover and Albedo
• Albedo is the fraction of total radiation that is
reflected by any surface.
Many clouds have a high albedo and therefore
reflect back to space a significant portion of the
sunlight that strikes them.
Clouds Reflect and Absorb Radiation
17.3 Temperature Controls
World Distribution of Temperature
 Isotherms are lines on a weather map that
connect points where the temperature is
the same.
• Isotherms generally trend east and west and
show a decrease in temperatures from the
tropics toward the poles.