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Variation of Insolation. Insolation can vary by changes in its intensity and duration . Variation in Intensity and Angle of Insolation. When insolation strikes the Earth at 90° (perpendicular to the Earth surface), it has maximum intensity . - PowerPoint PPT Presentation

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Variation of Insolation

Variation of Insolation

Insolation can vary by changes in its intensity and duration.Variation in Intensity and Angle of InsolationIntensity of Insolation = The rate at which solar energy is received by a given area per unit of time.

Insolation is measured in joules/m/s.

90When insolation strikes the Earth at 90 (perpendicular to the Earth surface), it has maximum intensity.There are several factors that can affect the intensity of insolation receives by a certain area on Earths surface.Factors that Affect the Intensity of InsolationEarths Shape

Earth is a sphere. Due to its shape, only one area of the planet can receive maximum intensity of insolation (Suns rays = 90).

All other areas of Earths surface would receive less direct insolation. Suns Rays90Factors that Affect the Intensity of InsolationEarths Atmosphere

When the Sun is directly overhead, the intensity of insolation is greatest.

The Suns radiation passes through a smaller area of the atmosphere.When the Sun is on the horizon (dusk/dawn), the intensity of insolation is smallest.

The Suns radiation passes through a greater area of the atmosphere. The radiation has a stronger chance of being reflected, absorbed or scattered in the atmosphere.Factors that Affect the Intensity of InsolationLatitude

During the Summer Solstice (June 21st), the maximum intensity of insolation (90) strikes the Tropic of Cancer 23 N90Factors that Affect the Intensity of InsolationLatitudeDuring the Winter Solstice (December 21st), the maximum intensity of insolation (90) strikes the Tropic of Capricorn 23 S

90Factors that Affect the Intensity of InsolationLatitudeDuring the Fall and Spring Equinox (Sept. 23rd and March 21st ), the maximum intensity of insolation (90) strikes the Equator 0

90Factors that Affect the Intensity of InsolationSeasonal Change

Due to the Earths tilted axis (23 ) and the its revolution around the Sun, the maximum intensity of insolation will vary between 23 N to 23 S throughout the year. Factors that Affect the Intensity of InsolationTime of Day

Maximum insolation will occur for an area when solar noon is reached.Solar NoonFactors that Affect the Duration of InsolationDuration of Insolation = The length of time insolation is received within a day.

Latitude and Seasonal Change

Factors that Affect the Duration of InsolationLatitude and Seasonal Change

During the summer solstice, NY state receives more direct insolation because the Sun is higher in the sky. Likewise, the apparent path the Sun takes from sunrise to sunset is greater.

Sun rises North of East and sets North of West

Summer Solstice = 15 hrs. of daylight

Apparent Pathways of of the Sun from NY StateDuring the winter solstice, NY state receives less direct insolation because the Sun is lower in the sky. Likewise, the apparent path the Sun takes from sunrise to sunset is small.

Sun rises South of East and sets South of West

Winter Solstice = 9 hrs. of daylight

During the equinoxes, NY state receives more insolation when compared to the winter solstice, but less when compared to the summer solstice. Likewise, the apparent path the Sun takes from sunrise to sunset is greater when compared to the winter solstice, but less when compared to the summer solstice.

Sun rises dueEast and sets dueWest

Equinoxes = 12 hrs. of daylight

Relationship of Surface Temperature to InsolationThe temperature of the Earths surface at a given location will change throughout the day .as well as throughout the year.A rise in temperature will occur when the intensity and/or duration of insolation received is greater than the energy lost by the earths surface radiation.Yearly Maximum and Minimum TemperaturesIn Westhampton Beach, the maximum intensity and duration of insolation is on June 21st the Summer Solstice. Yet, the maximum temperature here is not felt until late July or early August.Why???

Westhampton Beach, NYJune 2181F

Westhampton Beach, NYAugust 393F It takes time for the change in balance between energy received from the sun (insolation) and energy lost from the Earth (surface radiation) to occur.

After the summer solstice, the Earth continues to heat up due to a general increase in insolation. It isnt until a month later when the balance between incoming insolation and terrestrial radiation is the same.

The result? An increase in surface temperature!Yearly Maximum and Minimum TemperaturesThe same process occurs for when Westhampton Beach receives its minimum temperatures.

Westhampton Beach, NYDec. 2137F

Westhampton Beach, NYFebruary 320F It takes time for the change in balance between energy received from the sun (insolation) and energy lost from the Earth (surface radiation) to occur.

After the winter solstice, the Earth continues to lose heat due to a general decrease in insolation. It isnt until a month later when the balance between incoming insolation and terrestrial radiation is the same.

The result? An decrease in surface temperature!Times of Daily Maximum and Minimum TemperaturesIn Westhampton Beach, the maximum intensity of insolation would be at solar noon when the Sun is highest in the sky. Yet the maximum temperature of the day would not be at solar noon, but later in the afternoon.Again, there is a need for a balance to be reached between insolation and terrestrial radiation. It takes time for the Earths surface to heat up after solar noon and for the surface temperature to reflect this.

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