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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
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 COLDMeasures how HOT or COLD 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?
Answer: Convection (hot water moving)
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
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