Why does temperature vary so much in the world?
The answer: O LAMPNAS!

1) Ocean Currents: can either warm or cool a coastal area by approximately two degrees Celsius.

Note: Winds produce currents.
eg Los Angeles: California Current (cool)
Halifax: Gulf Stream Current (warm)

Further Information: Pages 147 to 148 in Planet Earth: A Physical Geography

2) Latitude: the further north you go in the northern hemisphere, the colder it gets.

Why?

a) Curvature of the earth: the sun strikes the earth in a very concentrated fashion at the equator, whereas at the poles, the sun's rays are much more spread out.

b) The Seasons: spring, summer, fall, and winter result in different amounts of heat coming to the earth. This is caused by the changing position of where the sun is directly overhead on the earth's surface during the year and the tilt of the earth's axis.

i.e. Mar. 21 (Vernal Equinox) and Sept. 21 (Autumnal Equinox): the sun is directly overhead at the equator.

Dec. 21 (Winter Solstice): the sun is directly overhead at the Tropic of Capricorn (23.5 S).

June 21 (Summer Solstice): the sun is directly overhead at the Tropic of Cancer (23.5 N).

Further Information: Pages 137 to 140 in Planet Earth: A Physical Geography

3) Altitude: the higher you go up, the colder it gets.

Why? Less dust, greenhouse gases, water vapour, etc. to trap heat coming up from the earth's surface.

Environmental lapse rate: 1 deg. C drop for every 150 m rise or 6.4 deg. C drop for every 1000 m

(Note: This rate applies to air that is still whereas the adiabatic rates apply to air that is being forced to rise and expand.)

Further Information: Pages 152 to 153 in Planet Earth: A Physical Geography

4) Mountain Barriers: impede the movement of cold air masses. This is due to the fact that cold air is dense and generally stays near to the ground.

eg Vancouver is shielded from most Arctic air masses by the Rockies and Coast Mountains.

Mountains can also result in warm winds descending down slope

eg a chinook: a warm wind that undergoes adiabatic heating. This westerly wind is dry and blows down the eastern side of the Rockies affecting cities such as Calgary.

Further Information: Pages 153 to 154 in Planet Earth: A Physical Geography

5) Prevailing Winds: southerly: brings warmer air
northerly: brings colder air

Further Information: Pages 141 to 146 in Planet Earth: A Physical Geography

6) Nearness to Water or Continentality: the closer a city is to a large body of water, the more moderate will be its temperatures (i.e. maritime climate), whereas the further away a city is from the water, the greater the temperature extremes (i.e. continental climate).

Further Information: Pages 149 to 151 in Planet Earth: A Physical Geography

7) Amount of Cloudiness:
Cloudy conditions generally produce cooler days (i.e. less solar radiation is able to reach the earth) and warmer nights (i.e. clouds act as a blanket to keep in heat emitted by the earth)

- the amount of cloudiness is dependent upon the air pressure
Low Air Pressure: cloudy conditions
High Air Pressure: clearer conditions

8) Slope of the Land (also known as Aspect)
- largely a micro-climatic control
- in the northern hemisphere, a north facing slope results in cooler temperatures whereas a south facing slope has warmer temperatures