CHAPTER 14Energy 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

GAS AND PARTICLES ABSORB SOLAR ENERGY

EARTH’S SURFACE

Earth’s surface absorbs solar energy

Clouds, gas & dust reflect and scatter light

Energy reflected back into the atmosphere

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 COLDCOLD a substance is.

• HOT = a lot of energy

• COLDCOLD = 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

More dense

Less dense

Convection Currents

• Warm air moves up, and cold air moves down

• Movement causes convection currents

• Convection currents move heat throughout troposphere

Warmer Air

Colder Air

Earth’s Surface

Heat transfer by radiation

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?

Answer: Conduction

If you were to touch the cookie sheet