Understanding Weather and the Environment , livre ebook

THE VISUAL GUIDES

Understanding
Weather
and The Environment

QA INTERNATIONAL

Understanding
Climate
and the
Environment

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Writers

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Researchers

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Agence Science-Presse
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Maxime Bigras
Patrice Blais
Yan Bohler
Mélanie Boivin
Charles Campeau
Jocelyn Gardner
Jonathan Jacques
Alain Lemire
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Nicolas Oroc
Carl Pelletier
Simon Pelletier
Frédérick Simard
Mamadou Togola
Yan Tremblay
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Reviewers

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Lucie Mc Brearty
Geneviève Théroux Béliveau

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Yves Comeau
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Marc Olivier
Judith Patterson

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Understanding
Climate
and the
Environment

QA INTERNATIONAL

4

6 | Earth’s atmosphere
8The atmosphere
10Atmospheric pressure
12The movement of air masses
14 Winds
16Prevailing winds
18Local winds
20 Tornadoes
22The power of tornadoes

46
44
42
40
38
37
36
34
32
30
28
26

Life and death of a cyclone

Inside a cyclone

The birth of a cyclone
Lightning and thunder
Thunderstorms
Rainbows
Dew and fog
Types of precipitation
Precipitation
Identifying clouds
Clouds
Humidity

24 | Precipitation

Ta b l e

48 | Meteorology

50
52
54
56
58
60
62

Measurement instruments

Measuring the temperature

Balloons and radar

Geostationary satellites

Polar-orbiting satellites

Weather maps

Reading a weather map

o f

80The consequences of
El Niño and La Niña
78El Niño and La Niña
76Temperate climates
74Polar climates
72Tropical climates
70Desert climates
68Climates of the world
66The seasonal cycle
64 | Earth’s climates

c

o

n

82 | The environment
84The biosphere
86 Ecosystems
88 Soil
90 The water cycle
92The carbon and oxygen cycles
94The phosphorus and nitrogen cycles
96The greenhouse effect
98Global warming
100The ozone layer

t

102
104
106
108
110
112
114
116
118
119
120
122

e

Sources of air pollution
The effects of air pollution
Acid rain
Sources of water pollution
Water pollution
Treatment of wastewater
Soil pollution

Desertification
Nuclear waste
Pollution of the food chains
Selective sorting of waste
Recycling

n

t

s

124 | Glossary
126 | Index
128 |Photo credits

5

a thin gaseous layer that
The air that we breathe comes from the atmosphere,
surrounds Earth
and protects it somewhat from solar radiation. Like all other matter, air has weight,
but this weight varies greatly depending on altitude and temperature. Variations in pressure cause atmospheric

movements and air masses to collide with or slide by each other. Winds, light or strong, constant or unpredictable,

contribute to the

planet’s thermal equilibrium.

Earth’s atmosphere

8

10

12

14

16

18

20

22

The atmosphere
A thin protective layer

Atmospheric pressure
The weight of air

The movement of air masses
Fronts and depressions

Winds
Atmospheric circulation

Prevailing winds
Major atmospheric movements

Local winds
The result of relief features

Tornadoes
The most violent winds on Earth

The power of tornadoes
Killer whirlwinds

T h e a t m o s p h e r e

A thin protective layer

The atmosphere, defined as the gaseous envelope surrounding Earth, does not
have well-defined edges. Half of its air molecules are concentrated in a very thin
layer, 5 km thick, but there are still traces of air at more than 1,000 km altitude.
Because of their protective function, the different layers of the atmosphere
play an essential role in the existence of life on Earth. All of the major
Earth’s amtemteosoprohleoremone alaoso ccrugical phen.ere thn ihespmoat

THE COMPOSITION OF AIR

The composition of the atmosphere remains stable at all altitudes: nitrogen and oxygen
represent 99% of its volume. Other gases, including argon and neon, are also found in air,
but in much smaller quantities. The proportions of water vapor and carbon dioxide in the
atmosphere vary, but are always very small.

nitrogen
(78%)

SOLAR ENERGY

argon
(0.93%)

In the Sun’s core, nuclear fusion reactions maintain a
temperature of 15 million degrees. This huge amount
ofenergy, constantly radiated into space in the form
of Etsthar s’sfaurtengr ci,syaaeh electromadneca
enables life to develop on the planet.

Solar radiationcrevoes th
entire electromagnetic
spectrum.

oxygen
(21%)

carbon dioxide
(0.03%)

The atmosphereand
clouds reflect 30% of
solar radiation.

weather balloon
(35 km)

supersonic jet
(18,000 m)

airliner
(11,000 m)

Mount Everest
(8,848 m)

The mesosphereis tkm) oldehe c8– 0(05reyal ts
of the atmosphere. At its outside edge, the
temperature is as low as –100°C.
50 km

THE LAYERS OF THE ATMOSPHERE

Earth’s atmosphere is made up of layers. The lowest ones (troposphere,
stratosphere, mesosphere) have a relatively homogeneous composition but
widely varying temperatures. In the thermosphere (80–500 km altitude), the
temperature rises considerably, since this layer absorbs considerable solar
radiation. Above it is the exosphere, a zone where the few remaining
molecules of air escape Earth’s gravity.

The temperature of the stratospheretheove t abj sumk,)5– 0(51
tropopause (–57°C), rises to 0°C because of absorption of solar
radiation by stratospheric ozone.

The ozone layer,m k30d detutialteewylb 0nane2 main,
intercepts much of the ultraviolet radiation directed toward
Earth.

15 km

The tropopauseb redrob eht sihe tenweet
troposphere and the stratosphere. Its altitude
varies depending on the season, the temperature
on Earth’s surface, the latitude, and the
atmospheric pressure.

The tops of cumulonimbush, reaccan uds col
and even go beyond, the edge of the troposphere.

The skylu bis rom eiaacsu eebterscatles lecu
mainly short-wavelength radiation, which
corresponds to the color blue in the visible
spectrum.

Most meteorological phenomena occur in the
troposphere(0–15 km), the part of the atmosphere
that contains almost all water vapor.

At sea levelf o,raperetuegarmet eht eva
the atmosphere is 15°C.

9

Earth’s atmosphere

Atmospheric pressure
The weight of air

Because molecules obey the laws of gravity, the molecules in the gases that make up
Earth’s atmosphere have a certain weight, which we bear constantly without being
aware of it. Atmospheric pressure is the force that air exerts by weighing on a given
area. At sea level, this pressure is equivalent to an average of 1,013 hPa, or 1.013 kg
2
per cm .
Earth’s atmosphere
Various factors, such as altitude and temperature, can create zones of high and
low atmospheric pressure. These variations are directly linked to major
meteorological phenomena.

10

HOW AIR PRESSURE IS MEASURED

The mercury barometer is used to measure atmospheric
pressure. Air presses on the mercury contained in a
reservoir, forcing it to rise in an evacuated tube. The
pressure exerted by the air is measured according to
the level reached by the mercury. For a long time, the
height of the mercury was the unit of measurement of
atmospheric pressure. Today, the International System
uses the hectopascal (hPa): 1,000 hPa is equivalent to
the pressure exerted by a 1 kg mass on an area
2
measuring 1 cm.

vacuum

THE INFLUENCE OF ALTITUDE ON ATMOSPHERIC PRESSURE

At sea level, the
height of the
mercury i