Transcript Climate and Weather I

Unit 2 Chapter 2
Canada’s Physical Geography
Climate and Weather
Part I
• Climate, besides landforms, affects all
Canadians and their sense of identity.
• Meteorology is the science of weather.
• Climate is how we describe the patterns
of weather conditions.
What Are The Elements of
Climate?
• The earth has “controls” like a thermostat,
that act upon the elements to produce
different types of weather and climate.
Global Factors:
Latitude
• As latitude increases, the intensity of the
sunshine decreases.
• The total number of daylight hours is
slightly greater at higher latitudes than at
the equator, but areas closer to the
equator have more intense radiation and
are much warmer than polar regions.
(Figure 2.15)
Air Masses and Wind
• If a volume of air remains in a place long
enough, it will take on some of the
characteristics of that place.
• Air masses have different characteristics and
names depending on if they are over land or
water. (Figure 2.16)
• Air masses over bodies of water or areas of
land have different characteristics, and
names that reflect their origins:
•
•
•
•
Maritime Tropical: warm water makes the air warm & moist
Maritime Polar: cold water makes the air cold and moist
Continental Arctic: cold air makes the air cold and dry
Continental Tropical: desert makes the air hot and dry
• Canada experiences a change in weather
as a result of the changing pattern of air
masses.
• Air masses tend to travel from west to east
across Canada.
• The jet stream is a high (8000 – 15 000
m), fast (300 – 400 km/h) wind that flows
east across North America.
• The direction of the jet stream is caused
by the Coriolis effect, which results from
the rotation of the earth from west to east.
Ocean Currents
• Ocean currents move immense amounts of
heat and cold around the world.
• Air passing over an ocean current is
influenced by the characteristic temperature
of that current. (Figure 2.17)
• Westerly winds passing over coastal water of the
Pacific are often warm and humid.
• Easterly winds blowing over the waters off Labrador
coast remain cold and do not have a high moisture
content.
• Southerly winds from the Gulf of Mexico bring sticky,
humid weather to Canada in summer and the
occasional snowstorm in winter.
Clouds and Precipitation
• Cloud, masses of suspended solid or liquid
water particles, may form when water vapour
in the air cools below the temperature of
condensation.
• This temperature is called the dew point.
• Water or ice particles in clouds increase in
size due to condensation or collisions with
other particles.
• When these particles become large enough,
they may fall to the surface as liquid or solid
forms of precipitation.
• Air masses are also responsible for causing
precipitation.
• The three types of precipitation:
• Frontal precipitation – may be caused when one air
mass displaces another. (Figure 2.18)
• Convectional precipitation – may occur as a result
of vertical movement within a mass of air (Figure 2.19)
• Relief, or orographic, precipitation – occurs when
moist air moves over a mountain barrier. (Figure 2.20)
• The leading edge of an air mass is called a
front.
• Air masses and their fronts move from an
area of higher pressure to an area of lower
pressure.