Transcript CHAPTER 14 Energy in the Atmosphere

CHAPTER 14
Energy in the Atmosphere
Section 1, pages 462-465
ELECTROMAGNETIC WAVES
• Form of energy that can travel
through space
• Classified according to
wavelength
• Direct transfer of energy by
electromagnetic waves is called
RADIATION
Energy from the sun reaches the
Earth in the form of visible light and
infrared radiation and a SMALL
amount of ultraviolet radiation.
• MIXTURE OF ALL COLORS
•ROY G BIV
• RED AND ORANGE
• BLUE AND VIOLET
LONGEST
WAVELENGTH
SHORTER
WAVELENGTH
INFRARED RADIATION
• Energy with wavelengths LONGER
than red light
• Can be felt as HEAT
• Heat lamps in the cafeteria used to
keep food warm
ULTRAVIOLET RADIATION
• Energy with
wavelengths
SHORTER than violet
light
• Sunburns, skin
cancer and eye
damage are caused
by this radiation
Clouds, gas & dust
reflect and scatter
light
GAS AND PARTICLES
ABSORB SOLAR
ENERGY
Earth’s surface absorbs
solar energy
Energy reflected back
into the atmosphere
EARTH’S SURFACE
GREENHOUSE EFFECT
• Process by which
gases hold heat in the
air
• “Create a blanket”
around the earth that
holds heat in the
atmosphere
What are 3 forms of
radiation from the
sun?
ANSWER: VISIBLE LIGHT,
INFRARED RADIATION AND
ULTRAVIOLET RADIATION
How do the 3
forms of radiation
from the sun
differ?
Answer: They differ in
their WAVELENGTHS
What happens to the energy
from the sun that is
absorbed by Earth’s
surface?
It is changed into
HEAT (heating the
land or water)
WHY IS THE SKY
BLUE?
Short wavelength blue light is
scattered more by gas
molecules in the atmosphere
WHAT MIGHT CONDITIONS ON
EARTH BE LIKE WITHOUT THE
GREENHOUSE EFFECT?
More infrared radiation back from earth’s
surface would escape into space instead of
being held in the atmosphere, so the Earth’s
surface would be much COLDER!
Chapter 14 Lesson 2 Heat Transfer
Remember:
• Molecules make up solids, liquids, and
gases.
• Molecules are always moving.
• Molecules in a solid move
• Molecules in a gas move .
.
Thermal Energy
• Thermal Energy – total energy of motion
in the molecules of a substance. (How fast
the molecules are moving)
• The faster the motion, the more thermal
energy.
Examples
• Ice cube (solid) – very little thermal
energy
• Lemonade (liquid) – some thermal
energy
• Steam (gas) – a lot of thermal energy
Temperature
• Average amount of energy in motion
of the molecules
• Measures how HOT or COLD a
substance is.
• HOT = a lot of energy
• COLD = very little energy
Thermometers
• Air temperature – use a thermometer
• Thermometers contain liquids - mercury or
alcohol.
• Liquids expand when heated (causes
liquid to rise) and contract when cooled
(causes liquid to fall).
• In science, temperature is measured in
degrees Celsius.
Freezing and Boiling Points
of Water
• Freezing Point – 0  C
• Boiling Point – 100  C
Heat
• Heat – the energy transferred from a
hotter object to a cooler one.
• 3 different ways to transfer heat: radiation,
conduction, convection
Radiation
• Radiation – direct transfer of energy by
electromagnetic waves (can travel through
space).
• Examples: Sun ray’s warming you up, heat
from campfire
Conduction
• Transfer of heat through DIRECT
CONTACT
• Energy passed from fast-moving
molecules (HOT) to slower-moving
molecules (COOLER)
• Does not work well in liquids or gases
• Examples: Walking barefoot on hot
sand
Convection
• Transfer of heat by movement of a fluid
(liquid and gas)
• Example: using a hair dryer to blow dry
your hair
Heating the troposphere
• Earth’s surface absorbs solar energy (from
sun) and warms up
• Air near surface warms (radiation and
conduction)
• Convection causes most of heating
Heat and Density
• As molecules heat up, they spread
apart (less dense) and rise
• Colder air sinks, warmer air rises
Less
dense
More
dense
Convection Currents
• Warm air moves up, and cold air moves
down
• Movement causes convection currents
• Convection currents move heat throughout
troposphere
Colder Air
Warmer Air
Heat transfer by
radiation
Earth’s Surface
What type of heat transfer?
What type of heat transfer?
Answer: Convection (hot water moving)
What type of heat transfer?
What type of heat transfer?
Answer: Radiation – campfire warms you
What type of heat transfer?
If you were to touch the cookie sheet
What type of heat transfer?
If you were to touch the cookie sheet
Answer: Conduction