Radiation & Greenhouse_Gases_F10_Lect4

Radiation & Greenhouse_Gases_F10_Lect4 - Radiation &...

Info iconThis preview shows pages 1–15. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Fall 2010, Lecture 4
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Radiation Radiation describes a process in which energetic particles or waves travel through a medium or space Radiation is often referred to as electromagnetic radiation (EMR) It comprises both electric and magnetic field components These components oscillate in phase perpendicular to each other and perpendicular to the direction of energy propagation 2
Background image of page 2
Classification of radiation Electromagnetic radiation is classified into several types according to the frequency, or alternatively its related property wavelength, of the wave 3
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Frequency Frequency is the number of occurrences of a repeating event per unit time. The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency 4
Background image of page 4
Frequency Diagram 5 Sinusoidal waves of various frequencies Bottom waves have higher frequencies, and shorter periods, than those above Horizontal axis represents time
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Wavelength Wavelength of a sinusoidal wave is the spatial period of the wave, the distance over which the wave's shape repeats It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings 6
Background image of page 6
Wavelength Diagram Wavelength of a sine wave, λ, can be measured between any two points with the same phase, such as between crests, or troughs, or corresponding zero crossings as shown 7
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Relationship of Frequency and Wavelength λ = c/ν c is the speed of light in a vacuum, a fundamental constant of nature (cm/s) ν is the frequency, measured in cycles per second, now called hertz (cycles/sec) λ is the wavelength (cm/cycle) c = 29,979,245,800 cm/sec (29.979 x 10 9 cm/sec) 8
Background image of page 8
Radiation Classification Types Classification types include (in order of increasing frequency and decreasing wavelength) Radio waves Microwaves Infrared radiation Visible light Ultraviolet radiation X-rays Gamma rays 9
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
10 Visible Light Visible light, as perceived by the human eye, lies between approximately 400 to 700 nanometers
Background image of page 10
What is a Greenhouse? A greenhouse is a structure with a glass or plastic roof and frequently glass or plastic walls Greenhouses heat up because incoming visible solar radiation from the sun is absorbed by plants, soil, and other things inside the building 11
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Greenhouse Physics - 1 Glass is transparent to this radiation The warmed structures and plants inside the greenhouse re-radiate this energy in the infra-red, to which glass is partly opaque, and that energy is trapped inside the glasshouse 12
Background image of page 12
Greenhouse Physics - 2 Although there is some heat loss due to conduction, there is a net increase in energy (and therefore temperature) inside the greenhouse Air warmed by the heat from hot interior surfaces is retained in the building by the roof and wall 13
Background image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
14 Incoming Radiation Some trace gases are known as “greenhouse"
Background image of page 14
Image of page 15
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 05/04/2011 for the course ESC 3704 taught by Professor Staff during the Spring '08 term at FAU.

Page1 / 67

Radiation & Greenhouse_Gases_F10_Lect4 - Radiation &...

This preview shows document pages 1 - 15. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online