Insolation And Local Factors

IB SL

5 Main Factors: Insolation

• Height of the sun.• Height above sea level.• Distance from land and sea.• Prevailing Winds.• Ocean Currents.

Height Of The Sun• Lower latitudes (equatorial regions) have higher

temperatures than higher latitudes (Poles) this is as a result of the amount of heating that each area receives.

• Places near the equator receive direct heat on a small surface area, and experience little energy loss via absorption, scattering and reflection, as there is a relatively small amount of atmosphere to pass through.

• Towards the Poles, the surface area to be heated increases, as does the amount of atmosphere to pass through, increasing losses via, absorption, scattering, and reflection.

Height Above Sea Level

• The atmosphere is heated from ground level upwards via long-wave radiation.

• The higher up a mountain you go, the smaller the surface area available to heat the atmosphere above.

• This, in combination with a decrease in the ability of the air to retain heat results in lower temperatures.

Distance From Land And Sea• Land and sea have vastly different specific heat

capacities (the amount of energy needed to raise 1kg of a substance by 1 degree).

• They have different abilities to absorb, transfer and radiate heat energy.

• Generally, land surfaces respond to heating on a daily basis (diurnal) meaning that differences between day and night temperatures can be into double figures, but sea surfaces respond over a period of months and retain heat for longer.

• The sea heats up and cools down more slowly than the land, acting to moderate temperatures for coastal locations.

Prevailing Winds

• The temperature of a wind and the subsequent effect it has on an area is dependent on:

1.Where it originated. 2.The surfaces it has blown over.

• Winds coming from the land in winter can be exceptionally cold, whilst winds coming from the sea in winter will be mild in comparison.

Ocean Currents

• Ocean currents can be either warm or cold and they act to either raise or lower temperatures of the coastal areas they flow towards.

• The North Atlantic drift is the major current acting on the UK and subsequently raises temperatures above what they should be for places along the same latitude.

Local Factors: 1

Amount of cloud cover:• Little cloud in the day reduces the amount of

absorption, reflection and scattering that occurs, allowing for more insolation to reach the Earth.

• At night, the same situation allows more heat to escape into the atmosphere - lowering temperatures.

• At night, cloud acts to trap heat in the lower atmosphere - moderating temperatures.

Local Factors: 2

Aspect:• The way a slope (land) faces can have a large

impact on the amount of insolation received. • This becomes important when planting crops

in valleys, as one slope will be cooler than the other, leading to a shorter growing season.

Activity

• Using Section 6; P179 plus P183-186 from Essential AS Geography, answer the following...

1. What are the defining differences between Weather and Climate?

2. How do the following factors alter temperatures in different areas: Albedo, Ocean Currents, Air Masses, and Cloud Cover?

3. How can development in an area change temperature? Why?