Insolation and the Seasons

Unit 6

Solar Radiation and Insolation

Solar Radiation and Insolation

Sun emits all kinds of E E.Most of the E E is visible light.

Sun emits all kinds of E E.Most of the E E is visible light.

Effects of Atmosphere on Insolation

Effects of Atmosphere on Insolation

The insolation reaching the surface is diff. from what reaches the upper atmosphere.

Visible light is mostly transmitted through to the ground.

The insolation reaching the surface is diff. from what reaches the upper atmosphere.

Visible light is mostly transmitted through to the ground.

Absorption of Ultraviolet and

Infrared

Absorption of Ultraviolet and

InfraredAlmost all UV rays are absorbed by the ozone

Recently ozone has been reduced. Mainly over the poles.

UV rays are a direct cause of skin cancer.

Almost all UV rays are absorbed by the ozone

Recently ozone has been reduced. Mainly over the poles.

UV rays are a direct cause of skin cancer.

Infrared waves are absorbed by gases in the atmosphere. CO2, CH4, H2O vapor.

Infrared waves are absorbed by gases in the atmosphere. CO2, CH4, H2O vapor.

Reflection and Scattering

Reflection and Scattering

Clouds cause a lot of reflection of insolation. Some E E does make it through, but is scattered.

This is caused by aerosols.As the amount of aerosols increases the amount of light scattered increases and the less E E reaches Earth.

Clouds cause a lot of reflection of insolation. Some E E does make it through, but is scattered.

This is caused by aerosols.As the amount of aerosols increases the amount of light scattered increases and the less E E reaches Earth.

Factors that affect Absorption and

Reflection

Factors that affect Absorption and

ReflectionAngle of insolationSurface characteristics

Angle of insolationSurface characteristics

Angle of IncidenceAngle of Incidence

The angle at which E E is striking the surface.

Higher the sun the higher the angle = warmer surface and air

The angle at which E E is striking the surface.

Higher the sun the higher the angle = warmer surface and air

Land and Water HeatingLand and Water Heating

H2O heats up more slowly and cools more slowly than land.

H2O heats up more slowly and cools more slowly than land.

Greenhouse EffectGreenhouse Effect

Much of the heat re-radiated back toward space never leaves the atmosphere.

The long infrared waves can be absorbed by the gases in the atmosphere.

Gases are called greenhouse gases.

Much of the heat re-radiated back toward space never leaves the atmosphere.

The long infrared waves can be absorbed by the gases in the atmosphere.

Gases are called greenhouse gases.

This keeps Earth’s surface at an average temp. of 59 degrees F.

If all heat absorbed was re-radiated the temp. of Earth’s surface would be 0 degrees F.

This keeps Earth’s surface at an average temp. of 59 degrees F.

If all heat absorbed was re-radiated the temp. of Earth’s surface would be 0 degrees F.

Variation of Insolation

Variation of Insolation

Varies by angle of intensity and duration of intensity.

A 90 degree angle is the strongest. 0 degrees is the weakest.

Varies by angle of intensity and duration of intensity.

A 90 degree angle is the strongest. 0 degrees is the weakest.

Effect of Earth’s Shape

Effect of Earth’s Shape

Sun’s E reaches Earth in a bundle of parallel rays. If Earth were flat, all angles of insolation would be 90 degrees.

Sun’s E reaches Earth in a bundle of parallel rays. If Earth were flat, all angles of insolation would be 90 degrees.

Effect of LatitudeEffect of Latitude

Intensity of insolation is greatest at the equator at each of the equinox.

At the time of the summer solstice, insolation is greatest at 23 1/2 N.

Winter solstice, greatest is at 23 1/2 S.

Intensity of insolation is greatest at the equator at each of the equinox.

At the time of the summer solstice, insolation is greatest at 23 1/2 N.

Winter solstice, greatest is at 23 1/2 S.

Duration of InsolationDuration of Insolation

The time between sunrise and sunset.

This time varies with latitude and seasons.

U.S.- Longest on June 21, shortest on December 21, and about 12 hrs. on March 21 and September 23.

The time between sunrise and sunset.

This time varies with latitude and seasons.

U.S.- Longest on June 21, shortest on December 21, and about 12 hrs. on March 21 and September 23.

Surface temp. will increase as long as the amount of E gained is more than the amount of E lost.

Surface temp. will increase as long as the amount of E gained is more than the amount of E lost.

Yearly Max. and Min. Temperatures

Yearly Max. and Min. Temperatures

Max and min temps do not occur on max and min insolation days.

Daily max. and min. are not at solar noon.

Max and min temps do not occur on max and min insolation days.

Daily max. and min. are not at solar noon.

Heat Budget and Climate

Heat Budget and Climate

Heat budget- the result of the balance between the total amount of energy gained and the total amount of energy lost. (average temp. of an object)

Heat budget- the result of the balance between the total amount of energy gained and the total amount of energy lost. (average temp. of an object)

Long-term changes in heat budget can result in climate changes.

Long-term changes in heat budget can result in climate changes.

Ice ages, Warm periodsIce ages, Warm periods

Earth’s heat budget has shifted in the past for long periods of time.

A cold shift creates glaciers that advanced all the way to the middle latitudes. Warm shifts have little glaciers.

Earth’s heat budget has shifted in the past for long periods of time.

A cold shift creates glaciers that advanced all the way to the middle latitudes. Warm shifts have little glaciers.

El Nino and La NiniaEl Nino and La Ninia

Every 2-10 yrs. The normally cold waters of the eastern Pacific Ocean, off western South America, are replaced with warmer water.

El Nino causes world wide flooding, drought, and heat waves.

Every 2-10 yrs. The normally cold waters of the eastern Pacific Ocean, off western South America, are replaced with warmer water.

El Nino causes world wide flooding, drought, and heat waves.

Global WarmingGlobal Warming

Since 1860 the world’s average temperature has risen 2 degrees F.

This trend has scientist worried that human interaction with the environment could speed up the rate of warming.

Since 1860 the world’s average temperature has risen 2 degrees F.

This trend has scientist worried that human interaction with the environment could speed up the rate of warming.

Causes of Heat Budget Shifts

Causes of Heat Budget Shifts

Solar E- the E output of the sun is related to sunspot activity. (11 yr. cycles)

When there are a large number of sunspots E from the sun increases by .1 to 1% more.

Solar E- the E output of the sun is related to sunspot activity. (11 yr. cycles)

When there are a large number of sunspots E from the sun increases by .1 to 1% more.

Change in tilt and orbit of Earth: over periods of thousands of years the tilt of the axis changes a couple of degrees.

The amount of eccentricity also changes.

When the cycle of these two factors change together, summers may be cooler and winters warmer with more precipitation.

Change in tilt and orbit of Earth: over periods of thousands of years the tilt of the axis changes a couple of degrees.

The amount of eccentricity also changes.

When the cycle of these two factors change together, summers may be cooler and winters warmer with more precipitation.

Another CauseAnother Cause

Volcanic eruptions: volcanic ash and other aerosols such as sulfur get into the stratosphere and reflect more E E than normal.

Volcanic eruptions: volcanic ash and other aerosols such as sulfur get into the stratosphere and reflect more E E than normal.