electromagnetic energy in the atmosphere

energy

Energy travels through space or material. This is obvious when you stand near a fire and feel its warmth or when you pick up the handle of a metal pot even though the handle is not sitting directly on the hot stove. Invisible energy waves can travel through air, glass, and even the vacuum of outer space. These waves have electrical and magnetic properties, so they are called electromagnetic waves. The transfer of energy from one object to another through electromagnetic waves is known as radiation. Different wavelengths of energy create different types of electromagnetic waves (Figure 1.1). The wavelengths humans can see are known as visible light. When viewed together, all of the wavelengths of visible light appear white. But a prism or water droplets can break the white light into different wavelengths so that separate colors appear (Figure 1.2). What objects can you think of that radiate visible light? Two include the Sun and a light bulb. The longest wavelengths of visible light appear red. Infrared wavelengths are longer than visible red. Snakes can see infrared energy. We feel infrared energy as heat. Wavelengths that are shorter than violet are called ultraviolet. Can you think of some objects that appear to radiate visible light, but actually do not? The Moon and the planets do not emit light of their own; they reflect the light of the Sun. Reflection is when light (or another wave) bounces back from a surface. Albedo is a measure of how well a surface reflects light. A surface with high albedo reflects a large percentage of light. A snow field has high albedo. One important fact to remember is that energy cannot be created or destroyed it can only be changed from one form to another. This is such a fundamental fact of nature that it is a law: the law of conservation of energy. In photosynthesis, for example, plants convert solar energy into chemical energy that they can use. They do not create new energy. When energy is transformed, some nearly always becomes heat. Heat transfers between materials easily, from warmer objects to cooler ones. If no more heat is added, eventually all of a material will reach the same temperature.

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instructional diagrams

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questions

if you live in a desert, the best car to buy to avoid a hot interior is one that is

-->  a) white

b) yellow

c) blue

d) black

radiation transfers energy by electromagnetic waves.

-->  a) true

b) false

the law of conservation of energy states that energy

a) cannot be created

b) cannot be destroyed

c) can change forms

-->  d) all of the above

violet light has the longest wavelengths for visible light.

a) true

-->  b) false

plants convert solar energy to chemical energy.

-->  a) true

b) false

the measure of how well a surface reflects light:

a) mirroring

-->  b) albedo

c) refraction

d) prism

a snow field has a low albedo.

a) true

-->  b) false

why would it be adaptive for a snake to see infrared energy?

a) as a reptile, it can then know where to go to warm up on cold mornings.

b) as an animal, it can avoid locations where infrared radiation is high.

-->  c) as a predator, it is better able to locate a prey animal if it can see its body heat.

d) none of these.

this breaks up light into different wavelengths, separating light into different colors.

a) mirror

-->  b) prism

c) glass

d) screen

which two items radiate energy?

a) a mirror and a prism

b) the moon and jupiter

c) the moon and the sun

-->  d) the sun and a light bulb

diagram questions

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