Heat Transfer, Greenhouse Effect, Ozone Layer Notes

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Heat Transfer, Greenhouse Effect,
Ozone Layer Notes
How does the Earth get heated?
• Energy transfer from the sun
Energy
• The ability to do work or cause change
• Temperature
– The average amount of energy of motion of
each molecule (the measure of how hot or
cold something is)
• Gas
– Moving particles, the hotter they get the
faster they move
The atmosphere moves energy
• Energy moves by heat transfer
• There are 3 types of heat transfer
– Conduction
– Convection
– Radiation
Conduction
• The transfer of heat energy from one substance
to another through DIRECT contact
• The Earth’s surface heats the air (gas) molecules
directing above it
• Molecules of air gain energy when they collide
with the molecules in grains of hot sand.
Convection
• Transfer of energy
from place to place
by the motion of
gas or liquid (fluids)
• Up and down
movement of
molecules not the
side to side
movement
Density and Convection
• The atmosphere gets less dense at
higher altitudes
• Warm air is less dense than cold air
– Warm air has more energy, so
molecules move faster than cold ones
– This makes them collide more, then
they spread out
– More space between molecules = less
dense
Radiation
• The transfer of the Sun’s energy to the Earth’s
surface
• Solar radiation heats both the surface and the air
– Includes visible light
• Earth’s surface gives off a type of invisible radiation
called Infrared radiation
Earth’s absorption of Radiation
• 30% of incoming solar energy is reflected by clouds
• 70% is absorbed and becomes different forms of
energy
– Absorbed by oceans, landforms, and living things
(photosynthesis and respiration)
• This absorbed energy heats the Earth’s surface
Transfer of Energy
Gases Absorb and Give Off Radiation
The Atmosphere affects light in 4 ways.
1.
2.
3.
4.
Absorbs Light
Reflects Light
Lets Light Pass Through
Emits (Gives Off) Light
On sunny days more visible light gets to the earths
surface.
On cloudy days clouds reflect and absorb most of
the sunlight
Forms of Radiation We Cant See
• Ultraviolet Radiation
– More energy than the light
you can see
– Can cause sunburns and
other damage
• Infrared Radiation
– Less energy than the light
you can see
– Warms the materials that
absorb it
Ozone Layer Protects Life
• Ozone - O3
– Ozone in stratosphere is
called the ozone layer
– Protects life on Earth
– Absorbs harmful ultraviolet
radiation from sun
• Too much can cause
sunburn, skin cancer, and
can harm crops, plastic or
paint
– Lets other types of radiation
like visible light through
Greenhouse Effect
• Keeps Earth Warm
• Slow the movement of energy away from the Earth’s
surface
• Greenhouse gases
– Includes carbon dioxide, methane, water vapor, and
nitrous oxide
– Gases mix with gases in the air like nitrogen and
oxygen. Not its own layer
– Found in the troposphere
– Absorbs and emits infrared radiation
Animation

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