Electromagnetic Energy

Energy  Energy: The ability to do work  Earth has two sources of heat energy: a.External source: The energy provided by the sun b.Internal source: The decay of radioactive substances and compression inside the Earth

Electromagnetic Energy  Electromagnetic Energy: a type of energy that is given off in the form of transverse waves from all matter not at absolute zero  Transverse waves: vibrate at 90 degree angles to the direction in which they are moving  Visible light is the type of electromagnetic energy that we are most familiar with

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

Electromagnetic waves and us  Visible light is the only part of the electromagnetic spectrum that can been seen by humans  Infrared energy is often felt due to its heating effects  Ultraviolet waves causes the skin to tan or burn

Interactions Between Electromagnetic Energy and an Environment  Electromagnetic waves can interact with a material by: a. Refraction: bending in the wave causing a change in direction, caused by varying density

b. reflection: bouncing off of the material

c. scattered, or refracted and/or reflected in various directions d. Transmission through the material e. Absorption or taken into the material

 Dark-colored, rough surfaces absorb more sunlight than light-colored shiny surfaces  Dark objects are better at radiating heat energy than lighter objects  If 2 nearly identical cups of hot water were left outside at night, the darker one would cool faster

Texture  The rougher the surface is, the more energy it will absorb and the less it will reflect  Example: mirrors are smooth so they are shiny, therefore reflecting most of the incoming visible light

 Land warms up and cools down faster than water  Good absorbers of energy are good radiators of energy (land)- that means the faster something heats up, the faster it cools down

 Snow and ice reflect much of the insolation back into space  The sun is always low in the sky so sunlight is less concentrated  The sunlight has to travel through more of the atmosphere because it is low in the sky