Canada’s Physical Geography

Climate and WeatherPart I

Unit 2 Chapter 2

• Climate, besides landforms, affects all Canadians and their sense of identity.

• Meteorology is the science of weather.

• Climate is how we describe the patterns of weather conditions.

What Are The Elements of Climate?

• The earth has “controls” like a thermostat, that act upon the elements to produce different types of weather and climate.

Global Factors:

• As latitude increases, the intensity of the sunshine decreases.

• The total number of daylight hours is slightly greater at higher latitudes than at the equator, but area closer to the equator have more intense radiation and are much warmer than polar regions. (Figure 2.15)

Latitude

Air Masses and Wind• If a volume of air remains in a place long

enough, it will take on some of the characteristics of that place.

• Air masses have different characteristics and names depending on if they are over land or water. (Figure 2.16)

• Air masses over bodies of water or areas of land have different characteristics, and names that reflect their origins:

• Maritime Tropical: warm water makes the air warm & moist• Maritime Polar: cold water makes the air cold and moist• Continental Arctic: cold air makes the air cold and dry• Continental Tropical: desert makes the air hot and dry

• Canada experiences a change in weather as a result of the changing pattern of air masses.

• Air masses tend to travel from west to east across Canada.

• The jet stream is a high (8000 – 15 000 m), fast (300 – 400 km/h) wind that flows east across North America.

• The direction of the jet stream is caused by the Coriolis effect, which results from the rotation of the earth from west to east.

Ocean Currents• Ocean currents move immense amounts of

heat and cold around the world.• Air passing over an ocean current is

influenced by the characteristic temperature of that current. (Figure 2.17)

• Westerly winds passing over coastal water of the Pacific are often warm and humid.

• Easterly winds blowing over the waters off Labrador coast remain cold and do not have a high moisture content.

• Southerly winds from the Gulf of Mexico bring sticky, humid weather to Canada in summer and the occasional snowstorm in winter.

Clouds and Precipitation• Cloud, masses of suspended solid or liquid

water particles, may form when water vapour in the air cools below the temperature of condensation.

• This temperature is called the dew point.• Water or ice particles in clouds increase in

size due to condensation or collisions with other particles.

• When these particles become large enough, they may fall to the surface as liquid or solid forms of precipitation.

• Air masses are also responsible for causing precipitation.

• The three types of precipitation:• Frontal precipitation – may be caused when one air

mass displaces another. (Figure 2.18)• Convectional precipitation – may occur as a result

of vertical movement within a mass of air (Figure 2.19)• Relief, or orographic, precipitation – occurs when

moist air moves over a mountain barrier. (Figure 2.20)

• The leading edge of an air mass is called a front.

• Air masses and their fronts move from an area of higher pressure to an area of lower pressure.