Presentation on theme: "Insolation. Objective TSWBAT: Explain the factors affecting insolation Explain the relationship between temperature and insolation Describe evidence."— Presentation transcript:
Objective TSWBAT: Explain the factors affecting insolation Explain the relationship between temperature and insolation Describe evidence for Earth’s radiative balance Define insolation, radiative balance Describe the four ways the atmosphere is heated.
What could cause us to have different amounts of sunlight/insolation?
1. Angle 90 o (direct rays) most intense insolation < 90 o (less direct rays) least intense insolation
3. Latitude Fall/Spring – Equinox (March 21 st and Sept 23 rd ) Perpendicular (90°) at the Equator (0°) Angle of incidence decreases as latitude increases (lowest at the North Pole (90°N) and South Pole (90°S)) 12 hours of daylight everywhere Altitude of noon sun: 47° Not tilted toward/away from sun Sunrise/set - E W
Summer Solstice (June 21 st ) Perpendicular (90°) at the tropic of cancer (23 ½ °N) 12 hours of daylight at equator (0°) 15 hours of daylight 43°N (Cambridge) 24 hours of daylight 90°N 9 hours of daylight at 40°S 0 hours of daylight at 90°S Altitude of noon sun: 70.5° Tilted toward the sun Sunrise/set - NE NW
Winter Solstice Dec 21 st Perpendicular (90°) at the tropic of Capricorn (23 ½ °S) 12 hours of daylight at equator (0°) 9 hours of daylight 43°N (Cambridge) 0hours of daylight 90°N 15 hours of daylight at 40°S 24 hours of daylight at 90°S Altitude of noon sun: 23 ½ ° Tilted away from the sun Sunrise/set - SE SW
Duration of Insolation Means number of daylight hours If the angle of insolation is low, there is a small duration of insolation (low temperatures) Creates unequal distribution of heat Why does this happen? Tilted axis of rotation – greater amounts of insolation in the summer (northern hemisphere), less during the winter
Duration of insolation NY: Winter: 23 ½ o, 8 hours of daylight, low temperatures, Dec 21 st Summer: 70 o, 15 hours of daylight, high temperatures, high angle, high intensity Fall/Spring - 47 o 12 hours of daylight.
Radiative balance A condition in which a body gives off as much heat as it receives. Insolation from Sun = infrared energy from Earth http://www.ieagreen.org.uk/tecres/tecim2.jpg
Evidence for radiative balance: daily http://apollo.lsc.vsc.edu/classes/met130/notes/chapter3/gr aphics/t_diurnal3.free.gif
Evidence of Radiative balance 1. Hottest and coolest times of day (4pm (maximum radiative energy) and 6am(minimum radiative energy)) 2. Hottest and coolest times of year (July/Aug (maximum radiative energy) and Jan/Feb (minimum radiative energy))
Is Earth really in radiative balance? Radiative balance means insolation = re- radiation. Over long periods of time, Earth is in radiative balance. Temperatures taken year to year vary though (short periods).
Heating the atmosphere 1. Direct absorption of radiation from the sun 2. Re-radiation of long-wave radiation from earth’s surface 3. Conduction 4. Latent heat of condensation
1. Direct absorption of radiation from the sun Gases absorb long-wave and short-wave radiation Transferred into heat energy
2. Re-radiation of long-wave radiation from earth’s surface Short wave radiation is absorbed by earth Reradiates long wave infrared radiation also called terrestrial radiation Gases in the atmosphere absorb this infrared reradiation and are heated
3. Conduction Transfer of heat by direct molecular contact Not all heat energy in rocks reradiate back Some is through direct contact of the hot rocks with the atmosphere
4. Latent heat of condensation Water vapor condenses to liquid water - Release (condensation) of latent heat gain (evaporation) of latent heat – cooling effect
Ex) body sweat evaporates and draws heat away from your body. The heat is stored in water vapor and rises in the atmosphere. When it condenses, heat is releases as latent heat. Clouds form and massive storm systems Body sweat may help form a cloud!!