Temperature Flashcards
why does the earth have four seasons?
due to Earth’s tilt, i.e. the critical factor that influences the existence of seasons is the tilt of the earth’s axis
what are earth’s seasons regulated by?
the amount of solar energy received at Earth’s surface - this is controlled by two factors:
1. Angle at which sunlight strikes Earth’s surface
2. How long the sun shines at a particular latitude
how much is earth’s tilt?
23.5 degrees with respect to a vertical passing through its center
what is the importance of Earth’s tilt?
controls angle of sunlight, i.e. the intensity of light
the effect of Earth’s tilt is more important than the distance between the Earth and the sun
what is the intensity of radiation equal to?
the radiation striking the surface directly, Ro multiplied by the cosine of the zenith angle, Z between the radiation beam and a line that is perpendicular to the surface
what is polar day
the period from september 22 to march 20 in the Arctic. the sun does not set for about 6 months at the North Pole during this time
what is polar night
the period from september 22 to march 20 in the arctic where the sun does not rise for 6 months at the North Pole during this time
in the northern hemisphere when do the meteorological and astronomical seasons begin?
meteorological boreal winter, spring, summer and fall start on the 1st of december, march, june, september
astronomical boreal winter, spring, summer, fall start on the 21st of december, march, june, september
in the southern hemisphere, when do the meteorological and astronomical seasons begin?
Meteorological austral winter, spring, summer and fall start on the 1st of June, September, December, March
Astronomical boreal winter, spring, summer, fall start on the 21st of June, September, December, March
in the northern hemisphere, south-facing objects …
are exposed to more sunlight - implications for crops, house design
why is spring and summer in the Northern Hemisphere a week longer than fall and winter?
due to Earth’s elliptical orbit around the sun, the total number of days from spring to fall equinox is approximately 7 days longer than from fall to spring equinox
Do the longer days during the
summer in the high latitudes imply
that the summers are hottest in
those latitudes?
no, light must travel a longer distance due to the larger solar zenith angle; aerosols and air molecules also scatter and absorb radiation as it passes through the atmosphere before it reaches the surface
what are the two factors that cause the maximum surface insolation to be at 30 degrees North at Earth’s surface, instead of 23.5 degrees north at the Tropic of Cancer
- days are longer poleward of the Tropic of Cancer
- the Tropic of Cancer is more humid and cloudier, which reflects more sunlight back out to space, cooling the surface
what causes diurnal variations in temperature
the earth spinning around the sun as well as on its own axis
what do diurnal variations describe?
- surface temperature is coolest in the morning
- sunlight strongest at noon
- surface temperature peaks in the late afternoon (between 3-5pm on clear days and earlier on cloudy or hazy days)
