CLIMATE and WEATHER

What is Weather? The state of the atmosphere at any particular place or time. Described using such elements or variables as: 1. temperature 2. precipitation (type) 3. humidity 4. cloudiness 5. air pressure 6. wind speed and direction

Elements of Weather Wind Temperature Pressure Humidity Clouds Precipitation

WEATHER Always changing, exhibiting large fluctuations in the atmosphere from hour-to-hour or day-to-day

What is CLIMATE? climate is defined as an area's long-term weather patterns. The simplest way to describe climate is to look at average temperature and precipitation over time. Other useful elements for describing climate include the type and the timing of precipitation, amount of sunshine, average wind speeds and directions, number of days above freezing, weather extremes, and local geography .

What is CLIMATE? Climate is the average weather in a place over many years. While the weather can change in just a few hours, climate takes hundreds, thousands, even millions of years to change.

Weather vs Climate Climate Weather Forecast: By aggregates of Collecting weather statistics statistical data over periods of 30 years Study Climatology Meteorology Components precipitation, temp. Sunshine, rain humidity, sunshine, cloud cover, wind velocity winds, hail, fog, frost, hail storms snow, sleet, over a period of time freezing rain flooding, blizzards ice storms, heat waves

Effects on Climate Canada’s climate has so much variety because: It extends from a great distance from north to south Different elevations Coastal and inland regions produce different climate Wind and pressure systems move weather conditions from one part of the country to another Some very large lakes, such as the Great Lakes, also have an effect

Effects on Climate: Latitude The most southerly point in Canada is Pelee Island in Lake Erie (41ºN) The most northerly point in Canada is Alert (Ellesmere Island) (83ºN) latitude This large range in latitude has a major impact on Canada’s climate

Effects on Climate: Latitude distance from the equator is a key factor in whether a region is hot or cold The size of the land mass in which a region is located is also a factor

Effects on Climate: Latitude The energy from the sun that hits the earth at the equator covers a small area The same amount of energy that hits the earth at the 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

Effects on Climate: Relief and Elevation Relief refers to differences in elevation of the earth’s surface Mountain ranges act as barriers to the movement of air masses This is why Vancouver often has warm, rainy weather in winter, while Calgary, on the other side of the Cordillera, has cold, dry weather

Effects on Climate: Latitude If you were hiking to the top of a mountain, you would notice that the temperature drops steadily as you climb As the elevation gets higher, it gets colder As air rises, it expands because there is less air pressure. As the air expands, it loses heat

Continental Environments Areas far from oceans and large lakes in the interior of land masses have a CONTINENTAL CLIMATE The temperature range is great because there is no large body to moderate the hot temperatures of summer and the cold temperatures of winter

Maritime Environments Coastal locations have a MARITIME CLIMATE The temperature range between the highest average monthly temperature and the lowest average monthly temperature is relatively small and the level of precipitation is higher

The Effect of Water Bodies of water have a moderating effect on land temperatures Oceans and large lakes heat up and cool down more slowly than land masses In summer, a body of water remains cooler than the land surrounding it Winds blowing from over the water keep the surrounding countryside cooler than it would be if the water body was not present

The Effect of Water In winter, bodies of water retain their heat and are warmer than the land Winds blowing off the water body warm the surrounding countryside Therefore, maritime locations near a large body of water, have cooler summers and milder winters than continental locations

Ocean Currents Climate is affected by ocean currents The temperature of an ocean current affects the tempeature of air that passes over it On the West Coast, the warm North Pacific Furrent heats the cools, moist air which passes over it This gives a mild climate to the coastal regions of B.C.

Air Masses Air masses - a large volume of air with the climate conditions of the area where it is formed Air masses originating from oceans contain moisture. As the air passes over land, the moisture is released in the form of precipitation Therefore, maritime locations are more likely to receive more precipitation than inland On the other hand, air masses originating from a continental climate will be dry

Winds and Pressure Systems Air pressure - air that has weight Differences in air pressure are created when the earth is heated to different temperatures Warmed air rising above the heated ground creates an area of low pressure When the rising air has cooled, it falls toward the earth and creates an area of high pressure

Winds and Pressure Systems Heating of the ground by the sun warms the air above it and causes the air to rise. This produces a low-pressure area 2. The air cools and sinks. This produces a high-pressure area 3. Air at ground level moves from high pressure to low pressure, creating winds

Winds and Pressure Systems Wind - moving air caused by the high-pressure areas moving toward low-pressure areas Prevailing winds - high and low-pressure belts that have created a pattern of winds. a.k.a. “westerlies’. They move in air masses that affect our weather

Winds and Pressure Systems POLAR FRONT - the boundary between cold, dry polar air and warm, moist tropical air Jet Stream - the current of fast-moving air located high in the atmosphere above the polar front In the winter this boundary between cold and warm air moves southward, allowing cold arctic air to flow farther southward into the United States In the summer, it moves northward, allowing warm air from the Gulf of Mexico to flow farther northward in to Canada’s interior The warm air masses and the cold air masses that meet at the polar front do not mix easily. Instead they often enter into a battle in the sky that we see as a storm