Canadian Geography 1202 Chapter 4: Weather

Weather and Climate Weather: the current atmospheric conditions (temperature, wind speed, precipitation, cloud cover,…) Climate: weather conditions over a long period of time (Botwood has a moderated or marine climate…)

Factors Affecting Canadian Climate Latitude Air Masses Altitude Landforms Nearness to Water

Latitude The further north and south of the equator, the colder it is. This is due to the earth’s spherical shape; the equatorial regions always receive more of the sun’s radiation.

Air Masses Air masses are large volumes of air which continually move from hot equatorial regions to cold polar regions as the earth rotates. They have an almost uniform temperature and moisture content; whether they are warm or cold depends on where they originate. The type of air mass over an area determines whether it will be warm or cold. Figure 2 Origin of air masses in winter Figure 1 Origin of air masses in summer

Altitude The higher the elevation/altitude, the colder it is. Why? – the air is thinner, so it hold less heat – it is further from the ground, which reflects or retains heat from the sun

Landforms The huge mountains of the west coast cause large amounts of orographic/relief precipitation on the windward side. The leeward side is in a rain shadow and receives little rain. Orographic Precipitation

Air Masses Frontal Precipitation: – Occurs when the leading edge (front) of a cold air mass meets the front of a warm air mass. The warm air is forced to rise above the cold air, it condenses and precipitation occurs.

Nearness to Water Water heats up and cools down more slowly than land. In summer, water is relatively cool compared to land. In winter, water is relatively warm. Areas near water have cooler summers and warmer winters than areas further away. The temperatures are moderated by the water.

Nearness to Water Ocean currents can be ‘warm’ or ‘cold’, which also influences climate on nearby landforms.

Nearness to Water Convectional Precipitation: – Moist air absorbs heat from the land, rises, condenses and rain falls. Often occurs on hot summer afternoons…hardly ever in Botwood!

Types of Canadian Climates Maritime Climate (close to water): cool summers, warm winters. (St John’s, Halifax, Vancouver,…) Continental Climate (inland): warm summers, cold winters. (Calgary, Saskatoon, Grand Falls-Windsor,…)