GEOG 131 Lecture Notes - Lecture 4: Solar Irradiance, Solar Constant, Wave Power
Document Summary
Insolation- incoming solar radiation: short wave energy. Attenuation- amount of atmosphere light has to pass through to get to earth"s surface. Solar constant- average amount of insolation: 345 watts/m^2. Earth"s orbit is nearly circular: closest to the sun in january (perihelion, farthest from the sun in july (aphelion, orbit does not cause seasons and spacial variability. Factors in uencing insolation: spreading of the solar beam, atmosphere attenuation. Latitudinal variations: equator- high sun angle= high energy, poles- low sun angle= more attenuation= less energy, mid= just right. Sun angle- measures angle between sun and horizontal. Important days in northern hemisphere: summer solstice- approximately june 21st, fall equinox- approximately september 21st, winter solstice- approximately december 21st, spring equinox- approximately march 21st. Circle of illumination- separates night from day. Polar night- when night lasts for a day or more. Polar day- when day lasts for a day or more.
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