chapter 2 Flashcards
Solar radiation emitted from sun which passes through the atmosphere and is reflected in
varying degrees by Earth’s surface and atmosphere and is detectable only during daylight.
Sun’s visible surface has temperature
6000K
99% of sun’s radiation fall between
0.2 - 5.6um (in the range of UV, Visible and IR), atmosphere quite transparent to incoming solar radiation
the sun emits many forms of electromagnetic radiation in varying quantities. as shown in the diagram, about
43 percent of the total radiant energy emitted from the sun is in the visible parts of the spectrum.
the bulk of the remainder lies in the near infrared (49 percent) and UV section (7 percent).
less than 1 percent of solar radiation is emitted as x-ray, gamma waves, radio waves
maximum radiation occurs
0.48um (in the visible range)
about 1/2 of solar radiation passes through the atmosphere and absorbed in
varying degrees by surface
terrestrial radiation is emitted from
the Earth and atmosphere
terrestrial radiation is emitted from the Earth and atmosphere
detectable both
day and night Earth’s ambient temperature -300K
detectable both day and night Earth’s ambient temperature -300K
Earth radiates ………………. times less than the sun
160,000 times
essentially all energy is radiated at
(invisible) thermal infrared wavelengths between 4-25um
maximum emission occurs at
97 um
Wavelengths covering most of Earth’s energy output are several times …………. than those covering most of the solar output
longer
Wavelengths covering most of Earth’s energy output are several times longer
than those covering most of the solar output. Therefore, refer to following
as:
terrestrial radiation - longwave radiation
solar radiation - shortwave radiation
Practically all of the energy that reaches the earth comes from the sun.
Intercepted first by the atmosphere, a small part is directly absorbed,
particularly by certain gases such as
ozone and water vapor.
Practically all of the energy that reaches the earth comes from the sun. Intercepted first by the atmosphere, a small part is directly absorbed, particularly by certain gases such as ozone and water vapor. Some energy is
reflected back to space by clouds and the earth’s surface.
Practically all of the energy that reaches the earth comes from the sun. Intercepted first by the atmosphere, a small part is directly absorbed, particularly by certain gases such as ozone and water vapor. Some energy is reflected back to space by clouds and the earth’s surface. only ………. of the solar radiation is absorbed by the earth’s surface
51%
Energy is transferred between the earth’s surface and the atmosphere in a variety of ways, including
- radiation 60%
- conduction (small)
- convection (15-20%)
The electromagnetic spectrum is the
distribution of electromagnetic radiation according to energy (according to frequency or wavelength).
the main band of EM are
IR
visible
UV
Less than 1% of solar radiation is emitted as
x-rays, gamma waves, and radio waves
The narrow visible part of the electromagnetic spectrum corresponds to the wavelengths near the
maximum intensity of the Sun radiation
White light may be separated into its spectral colors
(red, orange, yellow, green, blue, indigo and violet or “ROY G. BIV”) by dispersion in a prism.
Ultra violet
The region just below the
visible in wavelength is called the near ultraviolet
The region just below the visible in wavelength is called the near
ultraviolet. It is absorbed very strongly by
most solid substances, and in the atmosphere absorbed by ozone.
The region just below the visible in wavelength is called the near ultraviolet. It is absorbed very strongly by most solid substances, and in the atmosphere absorbed by ozone. The tissue effects of ultraviolet include
sunburn, but can have some therapeutic effects as well.
The region just below the visible in wavelength is called the near
ultraviolet. It is absorbed very strongly by most solid substances, and in the
atmosphere absorbed by ozone. The tissue effects of ultraviolet include
sunburn, but can have some therapeutic effects as well. The sun is a strong
source of
ultraviolet radiation
The tissue effects of ultraviolet include
sunburn, but can have some therapeutic effects as well. The sun is a strong
source of ultraviolet radiation, but atmospheric absorption eliminates
most of the shorter wavelengths.
radiation balance figure
IR
infrared light is the part of the EM spectrum that is invisible to human eye, but people still feel it as heat.
everything with a temperature above about 5 degrees kelvin emits IR radiation. the sun gives pff half of its total energy as IR, and much of its visible light is absorbed and re-emitted as IR
Viewed from above, the Earth makes a complete …………………….. rotation (spins on its axis) once in each 24-hour period.
counterclockwise
Viewed from above, the Earth makes a complete counterclockwise rotation (spins on its axis) once in each 24-hour period. This is why the Sun appears to rise in the east and set in the west. The Earth also revolves counterclockwise around the Sun once every
365 1/4 days
The Earth’s axis is not oriented vertically, but is tilted by
23.5 degrees
The Earth’s axis is not oriented vertically, but is tilted by 23.5 degrees.
The north end of the axis is always pointed toward the
North Star
The Earth’s axis is not oriented vertically, but is tilted by 23.5 degrees.
The north end of the axis is always pointed toward the North Star as the
Earth revolves around the sun. This tilt, combined with its revolution around
the Sun, causes
seasonal change
If the axis was not tilted, our year-round climate would be
rather boring and many places on Earth wouldn’t receive much light.
During our summer
the Northern Hemisphere leans toward the Sun in its revolution, there are more daylight hours, and the Sun’s angle is more perpendicular to us than at other times of year. The longer days and more concentrated sunlight result in more heating. (Shadows are shorter in the summer because the sun strikes Earth more directly).
During winter
the Northern Hemisphere leans away from the Sun, there are fewer daylight hours, and the Sun hits us at an angle; this makes it appear lower in the sky. There is less heating because the angled Sun’s rays are “spread out” rather than direct. (Shadows are longer because of the low er angle of the Sun).
During winter, the Northern Hemisphere leans away from the Sun, there are
fewer daylight hours, and the Sun hits us at an angle; this makes it appear
lower in the sky. There is less heating because the angled Sun’s rays are
“spread out” rather than direct. (Shadows are longer because of the low er
angle of the Sun).
In equatorial regions, the length of days and the directness of sunlight
don’t change as much. The further you get from the equator, the more dramatic the seasonal changes.
During the spring and fall
the Earth leans neither toward nor away from the Sun; daylight and nighttime hours are more equal and temperatures are moderate. (The shadow of an object is similar during these seasons)
Solstice refers to
the two times each year when the Sun’s strongest rays are furthest from the equator (north of it during our summer solstice and south during the winter). For the northern hemisphere, summer solstice
occurs around June 21st; we have the maximum number of daylight hours at that time. Winter solstice is around December 21st when we have the fewest daylight hours
Equinox
refers to the two times each year when the Sun’s strongest rays are directly hitting the equator. Everywhere on Earth has 12 hours of daylight on the spring and fall equinoxes. In the northern hemisphere, spring equinox occurs around March 21st and autumnal equinox around September 23d
