Upload
dana-collins
View
226
Download
0
Tags:
Embed Size (px)
Citation preview
Weather &
Climate
Chapter 6
Weather & ClimateWeather:
Refers to the current, day-to-day, short term conditions of the atmosphere.
Weather & Climate
Weather: Wind speed Wind direction Temperature Type of precipitation Amount of
precipitation Cloud cover Humidity Air pressure Hours of sunshine.
Weather & ClimateClimate: Refers to the
long term trends / patterns in the weather for a certain area.
Different areas experience different climate.
Monthly, seasonal, yearly.
Climate OR Weather??Do the following phrases refer to weather or
climate?
Annual precipitation of 200 mm. Rain forecasted for tomorrow Tuesday. Normal July temperature averages 22˚ C Temperatures this week will range
between 20 & 30˚C
Climate OR Weather??Do the following phrases refer to weather or
climate?
It was unusually hot this summer. Grand Falls-Windsor had 15 cm of snow
this past weekend. Vancouver has an annual frost free
period of 233 days. Residents in Florida are preparing to take
shelter from a hurricane.
Factors that Affect Climate
1. Latitude2. Ocean Currents3. Winds / Air Masses4. Elevation / Altitude5. Relief (Mountain barriers)6. Nearness to water
Scattergraphs
1. Latitude The further you move away
from the equator the colder it gets.
As latitude INCREASES – temperature decreases!
The closer you go towards the equator the warmer it gets.
As latitude DECREASES – temperature increases!
1. Latitude (cont’d)
The reason for this is: The sun’s energy is
concentrated in small areas near the equator.
Over larger areas further from the equator…the earth’s shape!
Therefore the farther from the equator the sun’s energy spreads over a larger area.
Intensity and Duration!!
2. Ocean Currents Pages 58-59 Q 1-3. Warm versus cold ocean
currents. Areas near warm ocean
currents have temperatures warmer than areas near colder ocean currents.
2. Ocean Currents (cont’d)
Pages 58-59 Q 1-3. Warm air over warm ocean
currents colliding with cold air over cold ocean currents result in precipitation such as FOG!
Ie. St. John’s, NL where the COLD Labrador current collides with the warmer Gulf Stream (See p. 60)
3. Wind Understand the cause of
wind and how they affect climate
What is Wind? A wind is a horizontal movement of air across a surface. Vertical movements are currents or updrafts and downdrafts Caused by what???? Heat versus cold!! This can be related to convection cells.
What causes wind? Unequal heating Unequal heating causes pressure differences Cold, heavy air sinks = high pressure Warm, expanding air rises = low pressure Winds blow from high to low
Know that air blows from areas of high pressure to areas of low
pressure. The statement is fact. Think:
1. Air inside a balloon
High and low pressures in the earth’s atmosphere are responsible for wind
Define the terms wind & prevailing wind.
Wind: Is a horizontal movement of air
across a surface. It results from air masses of
different temperatures and humidity lying next to each other.
The resulting pressure variation causes “wind” to blow from high pressure areas to low pressure areas.
Prevailing Wind:
Is regular, predictable, normal wind direction for a given area or region.
Caused by global convection cells.
Named after the direction from which it comes
Prevailing Winds
Prevailing Winds
Summary of Prevailing Wind
Global highs and lows are due to uneven heating of the earth
Air moves FROM HIGH pressure TO LOW pressure creating winds.
Describe Orographic rainfall
A relatively warm, moist air blows off the sea
It is forced up by mountains (high relief)
Windward
Leeward Chinook
Orographic rainfall Air cools at higher altitude Cool air holds less moisture Consequently clouds condense
and rain falls Most rain falls on the windward
side of the relief Leeward side is often in a dry
rain shadow because the moisture has all been lost
Definitions Windward
The side of the mountain receiving the wind of the water/ocean
(consequently more precipitation as well) Leeward
The side of the mountain sheltered from the wind
(consequently receives less precipitation) Rain Shadow
The area located on the leeward side of a mountain that receives low amounts of precipitation.
Mainly due to the air that descends on the leeward side has “dumped” on the windward side.
Frontal rainfall / Cyclonic
Warm, moist air
FRONT
•Weather Front-2 fronts meet
•Hence the name frontal rain
Warm Moisture laden air meets cold air
Warm air is less dense & is forced up over the cooler, more dense air
Frontal rainfall
Warm Moisture laden air cools at higher altitude
Cool air holds less moisture
Consequently clouds condense and rain falls
Describe Convectional rainfall
Usually occurs in hot areas like tropics or continental summer
Sun heats the earth causing large amounts of water to evaporate
Hot air rises forming convection currents (hence the name) Warm Moisture laden air cools at higher altitude Cool air holds less moisture Consequently clouds condense and rain falls
•Often associated with thunder storms.
Air heated from the earth