Factors that Influence Climate – L.O.W.E.R.N.
There are 6 factors that affect climate. You can easily remember them by
using the acronym, L.O.W.E.R.N. These 6 factors can be divided into 2 groups –
those that affect climates globally and those that affect climate locally.
Latitude
Ocean Currents
Wind and Air Masses
Elevation
Relief
Nearness to Water
Global Climate Factors
Latitude
 The distance a place is located from the equator (degrees North or South)
 The closer you are to the equator, the hotter it is. As you move away from
the equator toward the North and South Poles, temperatures become
cooler. This is because the earth’s rounded surface (curvature) causes the
sun’s energy to be spread out over larger areas towards the poles.
Low angle of incoming
sunlight
Sunlight directly overhead
Low angle of incoming
sunlight
Ocean Currents
 Ocean waters travel in
paths called currents; some are warm and others are cold. The temperature
of an ocean current affects the temperature of the air that passes over it.
 Warm ocean currents raise the temperature of nearby land, while cold
currents lower the temperature.
 Canada’s west coast is greatly affected by the warm North Pacific Current,
creating a mild climate in coastal cities such as Victoria and Vancouver.
 Canada’s east coast is greatly affected by the cold Labrador Current and
warm Gulf Stream. The meeting of these two currents often results in damp
and foggy conditions – dangerous to ships and freighters.
Local Climate Factors
Elevation
 The height above the earth’s surface (or altitude).
 Mountains influence climate because the higher you go up, the colder the
climate is. In dry air, the temperature decreases at a rate of 1C/100m, and
in moist air at a rate of 0.6/100m.
Relief
 The difference in the height of an area of the earth’s surface.
 Air condenses as it rises up a mountainside. This causes relief precipitation.
The windward side of a mountain receives a lot of precipitation, while the
leeward (rain shadow) side receives quite little.
Mountain Range
Wind and Air Masses
 An air mass is a large volume of air that moves over an area of land bring
with it, the weather conditions of the area it formed over. Air masses are
characterized based on their moisture content and temperature.
Moisture:
 Maritime (m) – wet (formed over water)
 Continental © - dry (formed over land)
Temperature:
 Tropical (T) – hot (formed near the tropics)
 Polar (P) – cold (formed between 55N and 66N)
 Arctic (A) – very cold (formed over the Arctic)
 Wind is created by differences in air pressure in the atmosphere (winds
move from areas of high pressure to areas of low pressure). Low pressure
systems are the result of warm air rising; associated with condensation
(cloud-forming) and precipitation. High pressure systems are created by
cool air sinking; associated with clear and favourable skies.
 Prevailing Winds are the well-established patterns of winds blowing from
west to east over Canada. We call these prevailing winds “westerlies” and
they move air masses, affecting our weather.
 The jet stream is the west to east movement of air in the mid-latitudes
flowing at speeds of up to 400 km/hr at an altitude of between 8000 and
15,000 metres.
 There are 5 air masses that cover North America, and each one brings
certain weather conditions to various areas of the continent:
Nearness to Water
 Proximity to a large body of water (i.e. oceans, or large lakes)
 Bodies of water are a source of moisture. Winds carry moisture over nearby
land, creating a moderating effect on climate.
 Places located near a body of water are called maritime climates (i.e.
Halifax, Nova Scotia) and experience mild temperatures (small temperature
range) and large amounts of precipitation (more than 1000mm).
 Places located far from a body of water are called continental climates (i.e.
Regina, Saskatchewan) and experience cool temperatures (large
temperature range) and small amounts of precipitation (below 1000mm).
 Bodies of water can also affect places on a seasonal level. In the summer
bodies of water remain cooler than the surrounding land. When winds blow
over the surface of the water, the nearby land is cooled. In the winter,
bodies of water retain their heat and are warmer than surrounding areas of
land. When winds blow over the surface of the water, the nearby land is
warmed.