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Chapter 3
The Changing Weather
Chapter 3 Terms
 Condensation
 Orographic Condensation
Precipitation
Weather
 Convectional Condensation Air Masses
 Frontal Condensation
Continental Artic
 High Pressure System
Maritime Tropical
 Low Pressure System
 Climate
Maritime Polar
Front
Ocean Currents
Gulf Stream
Labrador Current
Weather Radar
Stations
Meteorologists
Radiosonde
Conditions leading to
Condensation
Snow
Snow forms when
water vapour
condenses at a
temperature below
the freezing point
Read pp. 33 - 36
Snow Storm
For a snowstorm to
happen – it needs
two things…
Snow
Wind
Low & High Pressure Systems
Low Pressure System – Air rising over a warm surface
High Pressure System – Cool air sinks towards the surface, pushing the
air underneath away
Why we get wind…
 Air over the North and South Poles sink, because it is cold, producing an area of
high pressure
 Air over the equator rises because it is hot, producing an area of low pressure
 The earth rotates on its axis once every day, so that a point on the equator travels
approximately 40000 km in 24 hours – a velocity of nearly 1700km/hr
 Winds in the northern hemisphere blow counterclockwise into a low pressure area
and clockwise out of a high pressure area
 An area between high and low pressure feels the effects of both circulations
 High winds can develop when areas of very high and very low pressure come close
together
Questions… Page 37 #’s 1 - 4
Factors which affect Climate
 Climate – average conditions of temperature
 Precipitation – rain, snow, humidity, pressure and wind
 Weather – conditions of the atmosphere over a short
period of time
They can all be demonstrated on a climate
graph…
Climate Graph
Consists of…
Temperature – on left of
graph – shown by a line
graph
Precipitation – on right
of graph – shown by a bar
graph
Months of the year – on
bottom of graph
Climate Graph Assignment
Factors which influence the
climate in Atlantic Canada

Latitude – because of the shape of the earth’s surface, there are parts of Atlantic
Canada which receive more intense sunshine than others

Air Masses – affect the climate because they take on the temperature and
humidity characteristics of the areas in which they originate

Ocean Currents – the waters of the world’s oceans are constantly in motion. Tides
move the water up and down while currents move water from place to place. The
major ocean currents have considerable influence on climate.

Proximity to Water – Areas very close to large bodies of water stay cooler in
summer and warmer in winter than areas inland

Elevation – As height increases, temperatures decrease, largely because air is so
much thinner at high altitudes
Read pp. 37 – 41
Questions…Page 42
Examining
Weather
Land & Sea – weather
observers note and
transmit information
about the state of the
atmosphere
From the Air – use radar
to detect, locate and
measure the amount of
precipitation in clouds
From Space – weather
satellites are used to
make long-term weather
forecasts
Weather Radar Station
Read pp. 43 – 45, Questions…Page 46
Read pp. 46 – 47, Questions…Page 48