1. Weather and Climate – Part 1

2. Weather or Climate?
The terms “weather” and “climate” are often used interchangeably. However, they are not the same.
Weather is the state of the atmosphere at a specific time (e.g. current atmospheric conditions)
Climate refers to long-term atmospheric trends. Climate is “average weather” measured on different time scales (usually 30 years)
Both involve characteristics such as precipitation, temperature, atmospheric pressure, wind speed

3. Current Weather Updated: Sunday, October 25, 2009, 14:00 EDT
What is Weather?
Defined as:
Day-to-day characteristics such as temperature, precipitation, humidity, wind speed/direction, cloud cover and air pressure
example: Weather Forecast - Ottawa, Ontario
Current Weather Updated: Sunday, October 25, 2009, 14:00 EDT
11°C a few clouds
Wind: W 22km/h
Wind gusts: 35km/h
Sunrise: 7:32
Sunset: 18:00
Relative Humiditiy: 50%
Pressure: kPa
Visibility: 32.0 km
Ceiling: unlimited

4. example: CLIMATE - Ottawa, Ontario
What is Climate?
Defined as:
The weather conditions of a place averaged over a long period of time
example: CLIMATE - Ottawa, Ontario
Ottawa has a semi-continental climate, with a warm, humid summer and a very cold winter
Winters in Ottawa are severe
Ottawa, like other cities in Ontario, enjoys a sunny climate

5. FACTORS AFFECTING CLIMATE
Use the acronym: “LOWER Water” L.O.W.E.R.N.
Latitude
Ocean Currents
Wind Currents (air masses)
Elevation
Relief
Near Water

6. LATITUDE
As latitude increases (North or South from the Equator) the temperature decreases. This is due to a decrease in ‘concentrated’ solar radiation towards the poles.

7. Latitude
Canada’s southern most point is Middle Island in Lake Erie (41N)
Canada’s northern most point is Cape Columbia, NU (83N)
This range of 42 degrees latitude is almost the same as the distance between Ottawa and the Equator
Distance from the Equator is very important as locations nearer the equator have warmer climates as the Sun’s energy is more concentrated over a smaller area

10. Latitude

11. Ocean Currents

12. Ocean Currents
Ocean currents transfer heat (or cold) from one area to another. For example the Gulf Stream carries warm water from the Gulf of Mexico along the East coast of North America. The Labrador current carries cold water from the Arctic south towards Newfoundland.

13. Labrador Current/ Gulf Stream
Temperature of an ocean current affects the air mass above
Warm, North Pacific current heats air above it, warming coastal B.C.
Cold Labrador current meets warm Gulf Stream moving north off coast of Newfoundland, creating foggy conditions (100 foggy days per year)

14. Winds (Air Masses) Air masses carry heat and moisture across the
landscape as they move from one area to another.
m: Maritime - coastal (high precip.)
c: Continental –inland (low precip.)
T: Tropical - between the tropics (warm)
P: Polar – originating at higher latitude than the circles (cool)
Examples:
mP: Maritime Polar
cT: Continental Tropical

15. Winds and Pressure
air masses that form over continents are typically dry
air masses that form over oceans contain moisture and release precipitation when they reach land air has weight which is measured as air pressure

16. Winds and Pressure warm air rises, creating a low pressure system
cold air falls, creating a high pressure system

17. Wind and Pressure

18. Prevailing Winds
air moves from high to low pressure areas, this is called wind prevailing wind in Canada is west to east (called westerlies)
this means that most weather systems move west to east across Canada

19. Polar Front / Jet Stream
the Jet Stream is a current of fast moving west to east air at high altitudes

20. THE NORTH AMERICAN JET STREAM

21. Elevation
Temperature decreases with elevation. It is increasingly cooler at higher elevations in the troposphere (first layer of the atmosphere)

22. Youtube
Earth: Climate and Weather - National Geographic - 24hToday (3:23mins)
Strangest Weather On Earth - S01E02 - Thunder Snow: (21:14mins):