Contributed by:
Satnam Singh
Unit 1: Weatherwise
1. Grade 5 Science
Unit 1:
2. What is the Atmosphere?
The air that surrounds the Earth.
Characteristics of Air
 Air has no shape or color
 You cannot smell or taste air
 Air takes up space
 Air has mass
 Air exerts pressure
3. Layers of the Atmosphere
1. TROPOSPHERE: Surface of Earth to 16km. All
weather happens here.
2. STRATOSPHERE: 16-50 km above Earth’s
surface. No weather here. Airplanes fly here.
3. MESOSPHERE: 50-80 km above Earth’s
surface. Meteors burn up here.
4. THERMOSPHERE: 200-500 km above Earth’s
surface. Satellites, Space Station are here.
4. Layers of the Atmosphere
5. What is Air Pressure?
It is the force with which air pushes against
the earth’s surface.
Why does air exert pressure?
Air has mass. That means it puts pressure
on things around it. It will press in (down).
If this is the case, why doesn’t the air
around us crush us?
Because there is air inside of us and it is
pushing back against the air outside of us.
6. The Sun:
How does the sun
 people?
 the earth?
 the weather
 the atmosphere?
1. HEAT: The sun heats up the earth’s
Cloud cover helps keep that heat in.
2. LIGHT: Light from the sun passes through the
atmosphere and provides light for people
and plants.
3. RADIATION: the earth’s atmosphere shields
7. … (UV) Ultraviolet rays are invisible, high
energy rays from the sun that can damage
eyes, cause skin cancer, and contribute to
global warming.
Compared to past decades, why do we need to
be more careful today about UV rays? How are
we more careful?
(CFCs) is
depleting the
Ozone Layer (a
layer of gas in
that blocks
dangerous UV
rays from
8. Water (a liquid) evaporates, changes into
water vapour (a gas) that rises into the
atmosphere. There, it cools, condenses into
tiny water droplets, and forms clouds.
There are 3 main types of clouds:
1. Cirrus Latin word for “tuft or curl of hair”
2. Cumulus Latin word for “heap or pile”
3. Stratus Latin word for “spread out”
 These clouds look thin and
 They are so high up that
are made up of bits of ice.
 They usually mean
weather is going to
 These are big and fluffy
clouds that look like
 Flat bottoms, low to the
ground, and tall, puffy
 May indicate the
of rain.
 These clouds look flat and
like blankets covering the
 “Overcast”… may lead to
drizzle and fog.
 In morning, precedes
In afternoon, follows
12. What do clouds
do for the Earth?
 Like a coat or blanket, clouds protect earth
the cold “outside”.
 They also prevent earth’s heat from
Which night do you think is colder - a clear,
starry night, or a cloudy night? Why?
A clear night will be colder because there is no
14. The Water Cycle
 EVAPORATION: Heat from the sun
evaporates water from oceans, lakes, trees,
 CONDENSATION: The rising water vapor
cools, turns to water droplets and comes into
contact with dust particles in the air to form
 PRECIPITATION: When the clouds become
too full of water droplets, rain, sleet or snow
16. Fog! 1
 Fog is nothing more
than a cloud on the
 When warm air flows 2
over cool land, water
vapor condenses into tiny
droplets. This is FOG.
 3 Types:
1. Ground Fog: 100 m
2. Valley Fog: 500 m
17. The sun heats the earth's
surface unevenly. This creates
air masses of different
temperatures. Warm air is
lighter than cold air. Cold air
masses push under hot air
masses, causing them to rise.
This movement of air is called
Winds are named for the
direction from which they
For example (in NL):
A northeasterly wind does
not blow TO the north east.
It blows FROM the north
east. It has a cooling
A southwesterly wind
blows FROM the south
west. It has a warming
19. Wind Chill Factor
A measure of how cold air
feels to the skin.
The actual temperature +
the chilling effect of the
20. When air masses have
STORMS differences in air
temperature and air
pressure, storms can form.
21. Thunder & Lightning
 Cumulonimbus clouds are
also called “storm clouds”.
They are dark grey and billow
up to 16 km high.
 They cause high wind,
lightning and thunder.
 See bottom of pp. 24-25 to
see how lightning and thunder
 Lightning is hot (24 000 ̊C)
and fast (120 000 km/h).
23.  A tube of air that
hangs from the
thunderstorm like an
elephant’s trunk.
 Occurs when a strong,
fast column
of warm air starts
 Acts like a vacuum
cleaner, sucking in air at
the bottom and whirling
it upwards, picking up
24. Did you know?
 Tornadoes can lift railway cars, destroy
houses, and ruin whole towns… in
 Some tornadoes have winds as fast as
500 kmh.
 No one knows why tornadoes form in
some storms and not others.
 There are nearly 100 tornadoes in
Canada each year.
26. Violent, cyclonic storms that form in tropical waters and
eventually make landfall, causing much destruction.
They are different only in where they happen):
Hurricane: Atlantic / Northeast Pacific
Typhoon: Northwest Pacific
Cyclone: South Pacific / Indian Ocean
See map, next slide…
28. • The low pressure center of these storms is called the
“eye of the storm”
• These storms have a powerful cyclonic (circular) wind
motion. In the Northern Hemisphere the winds go
counterclockwise, and in the Southern Hemisphere,