TOPIC 6

How does insolation vary in intensity?

• The angle at which the insolation strikes the ground changes throughout the day and throughout the year for all locations.

• Insolation will have the greatest intensity when the angle of insolation is 90° or striking perpendicular with the ground.

How is the surface temperature related to insolation?

• The higher the intensity of insolation, the greater the temperature.

If temperatures are related to insolation, why doesn’t the hottest temperatures occur when

insolation is the greatest (summer) or when the intensity is the greatest (solar noon)?

• The hottest temperatures do not occur during these times because there is a delay.

• This delay relates to the changing balance between the energy being absorbed, reradiated and then warming the air.

How does Earth’s shape affect the intensity of insolation?

• The earth’s shape affects the intensity of insolation because the surface is curved.

• The sun’s radiation reaches the earth in parallel rays. Generally, the higher the latitude the more spread out the sun rays are, thereby changing the concentration of energy.

How does latitude affect insolation?

• Latitude affects insolation because the intensity changes. The intensity of insolation is greatest at the equator during each equinox.

• On June 21st, the intensity is the greatest at the Tropic of Cancer (23.5°N)

• On December 21st, the intensity is the greatest at the Tropic of Capricorn (23.5°S).

• So, as you move away from these locations on the corresponding dates, the intensity decreases.

How does the duration of insolation affect temperature?

• The duration of insolation is how long the sun is out

• The longer the duration of insolation, the greater the insolation (In the N.hemisphere it occurs during the summer).

• This is a direct relationship

What is a heat budget and how can it be measured?

• A heat budget calculates the amount of heat the Earth loses or gains; the overall outcome.

• In other words, comparing the amount we gain from the Sun’s radiation and Earth’s interior heat source (gain) to the amount we lose by radiating heat into space (loose).

What can long term changes in the heat budget cause?

Long term changes in the heat budget can cause ice ages and warm periods

What is an ice age?

An ice age is a period when the heat budget shifts toward a loss and glaciers advance into the middle latitudes.

According to the Reference Tables, when was the last ice age?

On page 8 and 9 of the ESRT, the last ice age was in the Pleistocene approximately 1.6 billon to 10,000 years ago.

Other then ice ages and warm periods, what other climatic changes can occur?

• Other climate changes are • Global warming• El Niño• La Niña

What is El Niño and La Niña?

• El Niño is a warming event when normally cold waters of the eastern Pacific ocean are replaced with warmer waters.

• This can cause flooding, droughts, excessive and heat waves in different locations

• La Niña is the opposite, it is when normally cold waters in the eastern Pacific ocean are replaced with colder waters.

What might cause the heat budget to shift?

• Sunspots - darker regions on the Sun’s surface that have hotter temperatures . This can change the amount of radiation given off by the Sun.

• Changes in the Earth’s tilt and orbit. Over thousands of years the tilt has had some minor changes a few degrees. It has said to “wobble”. The eccentricity has also changed a minor amount.

What might cause the heat budget to shift? continued

• Deforestation – cutting down forests results in areas becoming drier and essentially hotter.

• Volcanic eruptions – major eruptions add more greenhouse gasses into the atmosphere.