Chapter 12

Factors of Climate:


L: Latitude

O: Ocean

E: Elevation
Near Water


Weather: Day to day characteristics of the atmospheric conditions.


Climate: A long-term pattern of weather.


Average Annual Temperature: Monthly average temperatures, added together and divided by 12. Used to compare the climates of different places.


- The distance from the equator is key when determining temperature and climate. The higher the latitude, the lower the temperature, and that’s the L of LOWERN.


Relief: The differences in elevation of the earth’s surface.


- Mountain ranges act as a barrier to the movement of air masses. This is why Vancouver has warm, rainy weather; while Calgary has cold, dry weather.


- Elevation also causes the temperature to change. The higher your elevation, the colder it gets. This is because the top is farther from the main base, and from the main mass of land, therefore it is colder. Another reason is that the atmosphere is thinner at higher elevations, not allowing it to trap as much heat.


Continental Climate:


The annual variation in temperature due to the lack of significant bodies of water nearby.

This climate is great because there is to body of water to moderate the hot temperatures of summer and cold temperature of the winter.


Maritime Climate:


The temperature ranges of the average temperature are not high and the level of precipitation is higher. This is because it is near a large body of water.

Moderating Effect:


Bodies of water have a moderating effect on land temperatures. Oceans and large lakes heat up and cool down more slower than land masses.


Ocean Currents:


- Ocean currents affect climate


- The temperature of an ocean current, affects the temperature of the air that passes it.


- For examples the warm North Pacific Current is heats the cool moist air that passes over it.


Air Masses: An air mass is a large volume of air with the climate conditions of the area where it is formed.


- Air masses created of the ocean contain a lot of moisture. As the air mass comes to the land it releases this precipitation as rain or snow.


Winds and Pressure Systems:


- The weight of air is called Air Pressure.


- Differences in air pressure occur when the earth is heated at different temperatures


- Air moves along the surface of the earth from high-pressure areas to low-pressure areas. This causes Wind. Around the world there are high- and low-pressure belts that have reacted a pattern of prevailing winds.


- Wind usually blows from west to east in Canada and the USA these winds are called the westerlies.


- The boundary where cold, dry polar air and warm, moist tropical air Is called the Polar Front


- High above in the atmosphere, above the polar front is the polar front Jet stream. This causes wind to blow from west to east


- In the winter this boundary between cold and warm air moves southward, allowing cold arctic air to flow farther southward into the United States.


Air may rise for the following reasons:


1. To cross an area of high elevation. This causes relief precipitations


2. Because it has absorbed heat from the earth’s surface. This causes convectional precipitation.


3. Because there is a cooler denser air mass flowing beneath is that forces it up. This causes cyclonic precipitation.


Relief Precipitation:


- Mountain barriers create relief precipitation. As moist air rises up the windward slope of a mountain range, it expands and cools. As air-cools, the rate of evaporation decreases, and the rate of condensation increases.


- This can result in an increase in the number of water droplets in the air.


- When the water droplets are too heavy to remain in the atmosphere, they fall as rain.


- Moisture content is usually measured in terms or relative humidity (RH).


- RH = (amount of moisture in air) / (Moisture-holding capacity) X 100%


Convectional Precipitation


- Convectional precipitation is very common in summer continental locations, such as the Prairie Provinces, Ontario and Québec.


- The warm air comes from the ground and forms puffy white clouds, through condensation.


Cyclonic Precipitation


- Cyclonic precipitation forms when a front forms between to different air masses.


- A cyclonic storm is a large low-pressure system that forms when a warm air mass and a cold air mass collide. This often occurs under the Polar front jet stream, which separates cold, dry arctic air, from warm moist tropical air.


- Most of the precipitation in the Prairies, Ontario, and Québec, and Atlantic Canada, especially in the winter, is cyclonic.