6WEATHER VS. CLIMATEWEATHER – is defined as day to day characteristics of the atmospheric conditions – for example, a rainstorm, a snowstorm, a hot sunny day, a windy day and so on…CLIMATE – is defined as a long-term pattern of weather. Climates influence many elements of our lives – for example, where we live, what clothes we wear, and so on…Canada’s climate has a great deal of variety because of four basic facts:1) Canada extends for a great distance from north to south, ) Different elevations produce different climate conditions, ) Coastal regions have different climates from inland regions, ) Wind and pressure systems move weather conditions from one part of the country to another
7Climate influences, and sometimes dictates, our daily activities and travels. In the summer, it can be hot or stormy, or it can be the perfect day for golf, baseball or going to the beach. In the winter, it can be extremely cold with heavy snowfalls and storms, which brings up travel concerns, heating concerns, and of course, whether or not it will be a snow day from school. When the weather is at extremes, we are very aware of it and schedule our activities accordingly.We can easily identify the climate and weather patterns that affects our daily routines. BUT, what are the factors that affect the type of climate that we experience?
8FACTORS THAT AFFECT CLIMATE L atitudeO cean CurrentsW indE levationR eliefN ear Water
9LATITUDEDistance from the equator is a key factor in whether a region is hot or cold.The southernmost territory of Canada, is comprised of a number of islands which form an archipelago in the Western Basin of Lake Erie. Pelee Island and Middle Island are situated just above the Canadian-American border at 41 degrees north latitude. The annual average temperature is 9.1oCAlert is the northernmost permanent settlement in the world. It is located at 83 degrees north latitude, on the north eastern tip of Ellesmere Island on the shore of the Lincoln Sea, in the territory of Nunavut in Canada The annual average temperature is –18.1oC
10LATITUDEThe energy from the sun that hits the earth closer to the equator covers a small area.The more northerly location is spread over a larger area because of the curvature of the earth.Places closer to the North and South Poles experience colder temperatures than those near the equator because the same amount of energy is spread over a larger area due to the curvature of the earth.* See figure 12-3 on page 129 in your text.
12OCEAN CURRENTSClimate is affected by ocean currents – Figure 12-7 page The temperature of an ocean current affects the temperature of the air that passes over it, making the air warmer or colder.
13OCEAN CURRENTS A Few Examples: West Coast: The warm North Pacific Current heats the cool moist air which passes over it. This gives a mild climate to the coastal regions of British Columbia.East Coast: The cold Labrador Current, which flows southward from the Arctic, cools the air of coastal locations in Labrador and northern Newfoundland.
14OCEAN CURRENTSWhat do you notice about the location of cold and warm ocean currents in relation to the equator?
16It is the wind that moves air masses and therefore causes weather. Air moves along the surface of the earth from high-pressure areas toward low-pressure areas. It is the moving air that causes wind.It is the wind that moves air masses and therefore causes weather.In Canada, the prevailing winds are ‘westerlies’ beacuse they originate and blow towards the east.
17Teperature decreases with an increase in elevation. Temperature drops at a rate of 1oC for every 100 meters of elevation (on average).When the Dew Point (when water vapor begins to condense) is reached, the rate of cooling slows to 0.6oC per meters because as water cools it realeases heat.
18RELIEFRelief refers to the differences in elevation of the earth’s surface.Mountain ranges act as barriers to the movement of air masses – therefore, for example, Vancouver often has warm, rainy weather in the winter and Calgary, on the other side of the Cordillera, has very cold dry weather.
19Water has a moderating effect on land temperatures. NEAR WATERWater has a moderating effect on land temperatures.Oceans and large lakes take a longer time to heat up then the surrounding land mass and a longer time to cool down.
20NEAR WATERIn summer, winds blowing over a body of water will keep the surrounding land cooler than it would be if the water body was not presentIn winter, the water reatins heat and is warmer than the surrounding land. Winds blowing off a body of water warm the surrounding land as a result.
22More from the Weather Network Website Cold Front Symbol Warm Front Symbol
23COMMON WEATHER TERMSFront:A front can best be described as the border between two different air masses.Cold Front:A cold front is the leading edge of cooler or colder air. It cuts into the space that is occupied by warmer air and eventually replaces it with a cooler/colder Air Mass. This happens as the cold air causes the warm air to rise up and over it. As the warm air travels upwards, it begins to mix with the cold air aloft and condenses to form clouds. You can usually expect scattered showers and thunderstorms along the front as it approaches.Warm Front:A warm front is the leading edge of a milder or warmer air mass. A warm front travels in such a way that it results in warm air replacing colder air. This happens as the warm air rises up and over the cold air below. As the warm air travels upwards, it begins to mix with the cold air aloft and condenses to form clouds. You can usually expect periods of rain or drizzle for many hours as the front approaches.
24COMMON WEATHER TERMSAir Pressure:(also known as atmospheric pressure)Is the amount of force wielded on a surface by the weight of the air above it. The unit for measuring air pressure worldwide is the kilopascal.Low Pressure Centre:Indicates an area of low atmospheric pressure. In a low, air is flowing counter clockwise into the centre of the Low. The air will rise and cool often resulting in clouds and precipitation.High Pressure Centre:Indicates an area of high pressure. In a high, air will slowly descend and flow out in a clockwise direction at the ground. Normally a high will bring mainly sunny skies to an area.
25COMMON WEATHER TERMS Jet Stream: Moderately strong winds grouped in a narrow stream in the atmosphere, usually in reference to horizontal, high altitude winds. The location and orientation of jet streams change from one day to the next. Weather patterns (hot/cold, wet/dry) are influenced by the position, strength and orientation of the jet stream (or jet streams).Dewpoint:The dewpoint is a measure of atmospheric moisture. It is the temperature at which air must be cooled in order to reach saturation (assuming that air pressure and moisture content are constant). As the surface of the earth cools at night, warm moist air near the ground is chilled and water vapour in the air condenses into droplets on the grass and other objects. Dew is particularly heavy on clear nights, when the earth cools rapidly. When a blanket of cloud insulates the earth, the cooling rate is slower. The greater the difference between the temperature and the dew point, the drier the air.Frost Point:The highest temperature at which atmospheric moisture will sublimate and form a deposit of interlocking ice crystals on a cooled surface.
26HOMEWORKUsing the Map of North America provided for you, draw, label and identify the air masses and ocean currents that affect Canada’s weather – use figure 12-7 on page 131 in your text book as a guide.* Don’t forget to make a legend and to add colour.
27but wait, there's more... Complete questions: # 1, 2, 3, and 4 a) – Page 139 in your text.* Write this down in your agenda if you have not done so already.