The Sun and Seasons
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According to the planetesimal hypothesis, the solar system formed from a large…
Slowly rotating “nebula”
When/what is it called when the Earth closest to the sun?
Perihelion, Jan. 3
When/what is called when the Earth is farthest from the sun?
Aphelion, July 4
How much matter does the sun contain from the original nebula?
99.9%
Solar mass is converted to…
Energy by fusion of hydrogen atoms
What does the sun emit?
Charged particles called SOLAR WIND
Seasonality
Refers to the variation in the sun’s altitude and the changing length of daylight that occurs over the year
As the Earth rotates on its axis, in the same direction, what does it produce?
• Diurnal rhythms • Coriolis effect • Even distribution of radiant energy along parallels
What is the Earths tilt?
23.5 degrees with respect to the ecliptic
What is the latitude of the sub-solar point (AKA solar declination)?
231⁄2° N and 231⁄2° S during the year
Why do you get a sunburn in summer, but not winter? Or in the tropics, but not in Vancouver?
The angle of incidence (of incoming radiation) and the strength of the solar beam affect the amount of heating
When is winter solstice?
December 21-22 @ 23.5°S
When is summer solstice?
June 20-21 @ 23.5°N
When is vernal equinox?
March 20-21 @ the equator
When is autumnal equinox?
September 22-23 @ equator
The modern atmosphere is made up of?
A mixture of ancient gases
Air
Is a simple mixture of gases which blend so thoroughly they behave as a single gas
Air density
Is the amount of gas molecules in a given volume
Air pressure
Is the weight of the atmosphere above a given point
The atmosphere can be divided into what 3 criteria?
• Composition • Temperature • Function
Troposphere
• Is from the surface - 12-18 km • It accounts for 90% of atmospheric mass and almost all water vapour, clouds, air pollution and life • Temperature decreases with altitude at the normal lapse rate of 6.4°C/km
Stratosphere
• Is from 18-50 km above the surface - The temperature increases with altitude (UV absorption)
Mesosphere
• Is from 50-80km above the Earth - The coldest portion (-90°C)
Thermosphere
• Is from 80-480km above the Earth - Big rise to 1200°C, but little actual heat