Electromagnetic Electromagnetic EnergyEnergy

EnergyEnergy

Energy: The ability to do workEnergy: The ability to do work Earth has two sources of heat energy: Earth has two sources of heat energy:

a.a. External source: The energy provided External source: The energy provided by the sunby the sun

b.b. Internal source: The decay of Internal source: The decay of radioactive substances and radioactive substances and compression inside the Earthcompression inside the Earth

Electromagnetic EnergyElectromagnetic Energy

Electromagnetic Energy: a type of energy Electromagnetic Energy: a type of energy that is given off in the form of transverse that is given off in the form of transverse waves from all matter not at absolute zerowaves from all matter not at absolute zero

Transverse waves: vibrate at 90 degree Transverse waves: vibrate at 90 degree angles to the direction in which they are angles to the direction in which they are movingmoving

Visible light is the type of electromagnetic Visible light is the type of electromagnetic energy that we are most familiar withenergy that we are most familiar with

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Some DefinitionsSome Definitions

Wavelength: The distance from one crest Wavelength: The distance from one crest to the next crest or the distance between to the next crest or the distance between any two corresponding points on two any two corresponding points on two consecutive wavesconsecutive waves

Electromagnetic waves Electromagnetic waves and usand us

Visible light is the only part of the Visible light is the only part of the electromagnetic spectrum that can been electromagnetic spectrum that can been seen by humansseen by humans

Infrared energy is often felt due to its Infrared energy is often felt due to its heating effectsheating effects

Ultraviolet waves causes the skin to tan Ultraviolet waves causes the skin to tan or burnor burn

Interactions Between Interactions Between Electromagnetic Energy and Electromagnetic Energy and an Environmentan Environment

Electromagnetic waves can interact with Electromagnetic waves can interact with a material by:a material by:

a. Refraction: bending in the wave causing a. Refraction: bending in the wave causing a change in direction, caused by varying a change in direction, caused by varying densitydensity

b. reflection: bouncing off of the materialb. reflection: bouncing off of the material

c. scattered, or refracted and/or reflected in c. scattered, or refracted and/or reflected in various directionsvarious directions

d. Transmission through the materiald. Transmission through the material

e. Absorption or taken into the materiale. Absorption or taken into the material

Dark-colored, rough surfaces absorb Dark-colored, rough surfaces absorb more sunlight than light-colored shiny more sunlight than light-colored shiny surfacessurfaces

Dark objects are better at radiating heat Dark objects are better at radiating heat energy than lighter objectsenergy than lighter objects

If 2 nearly identical cups of hot water If 2 nearly identical cups of hot water were left outside at night, the darker one were left outside at night, the darker one would cool fasterwould cool faster

TextureTexture

The rougher the surface is, the more The rougher the surface is, the more energy it will absorb and the less it will energy it will absorb and the less it will reflectreflect

Example: mirrors are smooth so they are Example: mirrors are smooth so they are shiny, therefore reflecting most of the shiny, therefore reflecting most of the incoming visible lightincoming visible light

Land warms up and cools down faster Land warms up and cools down faster than waterthan water

Good absorbers of energy are good Good absorbers of energy are good radiators of energy (land)- that means the radiators of energy (land)- that means the faster something heats up, the faster it faster something heats up, the faster it cools downcools down

Snow and ice reflect much of the Snow and ice reflect much of the insolation back into spaceinsolation back into space

The sun is always low in the sky so The sun is always low in the sky so sunlight is less concentratedsunlight is less concentrated

The sunlight has to travel through more of The sunlight has to travel through more of the atmosphere because it is low in the the atmosphere because it is low in the skysky