Unit 5

UNIT 5.
ATMOSPHERE:
WEATHER AND
CLIMATE
1. The Earth´s Atmosphere.
2. The properties of air.
3. Atmospheric dynamics: weather and climate.
4. The Earth´s climates

1. THE EARTH´S ATMOSPHERE
 Remember: the Earth´s atmosphere is a gaseous layer that surrounds
the planet, provides oxygen and protects us from solar radiation.
The atmosphere is divided into
different layers:
1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere (Ionosphere)
5. Exosphere.
Most meteorological
phenomena, such as cloud
formation, wind and rain occur
in Troposphere.

The layers of the atmosphere
1. Troposphere (0-12 Km)
 The main meteorological phenomena happen here.
 It is the closest layer to Earth's surface.
 It is the layer we live in.
 higher altitude=colder temps (temperatures drop by 0, 65 ºC for every 100 m of altitude).
2. Stratosphere (12-50 km).
 Ozone layer is here. It absorbs ultraviolet radiation from the sun.
 Higher altitude=warmer temps.
3. Mesosphere (50-100 km)
 Where meteors and comets are destroyed
 higher altitude=colder temps (temperatures sometimes reach -100 ºC).
4. Thermosphere (Ionosphere) (85-600 km)
 Solar radiation produces electrically-charged.
 Borealis auroras are here.
 Higher altitude=warmer temps (reach up to 1500 ºC).
5. Exosphere (600-10.000 km).
 The outermost layer, where satellites orbit Earth.

2. THE PROPERTIES OF AIR
Composition of gases. Air is a mixture of gases: 78%
nitrogen, 21% oxygen and various other components such as
water vapour.
Temperature.
Warm air (lower levels) weighs less (became lighter)and rises.
Cool air (higher levels) weighs more (became heavier) and
decreases or fall down.
Atmospheric pressure. Is the term used to describe the
pressure exerted on Earth by the weight of the air. It is
measured with a barometer.
Both altitude and temperature determine atmospheric pressure.
Relatively humidity. It refers to the amount of water vapour
that air contains. When water vapour begins to condense into
droplets, clouds are formed.

 The most important properties of air

3. ATMOSPHERIC DYNAMICS
3.1. WEATHER AND CLIMATE
 The Sun´s rays warm up the atmosphere and our planet´s surface.
The energy from the Sun is responsible for the Earth´s weather and
climate.
 You have to distinguish these two concepts:
 Weather is the state of the lower layers of the atmosphere at a
certain time and place on Earth.
 The science that deals with predicting what the weather will be like in a
certain zone is called Meteorology.
 Climate refers to the state of the weather in a certain region of the
planet over a long period of time. It is necessary to analyze a
region in 30 years intervals to establish the climate of a region.
 The science that studies different types of climate is referred to
as Climatology.

3.2.FACTORS THAT INFLUENCE
WEATHER
 Weather can be determined by many factors:
A. ATMOSPHERIC PRESSURE.
B. TEMPERATURE.
C. WIND.
D. HUMIDITY AND PRECIPITATION
 https://study.com/academy/lesson/temperature-clouds-wind-humidity-on-
the-atmospheric-cycle.html

A. ATMOSPHERIC PRESSURE
 Atmospheric pressure is the weight of air over a particular Earth´s
surface. It is measured in hectopascals (hPa).
 It varies from one place to another and depends on:
Altitude: atmospheric pressure
is lower at higher altitudes. For
example, the amount of air at the
top of a mountain is less than at
the base.
Temperature: warm air weighs
less than cold air. As a result:
 warm air rises and exerts
less pressure on the Earth´s
surface,
 while cold air descends and
exerts more pressure.

Weather maps
 Atmospheric pressure can be represented on a map, where the points of equal
atmospheric pressure are joined through a few lines: isobars. When isobars
are close together, in this area is very windy.
 You can see A (Anticiclón. In English language H: high pressure area) and B
(Borrasca. In English language L: low pressure area or depressions).
 In Spain there is an area of high pressure (more than 1013 hPa), so the
weather is stable. However, in Northern Europe there is an area of low
pressure (less than 1013 pHa), so the weather is unstable.
Anticyclones (H): are areas of high
pressure (more than 1013 hPa).
They produce stable weather.
Depressions (L): are areas of low
pressure (less than 1013 hPa). They
produce unstable weather.

B. TEMPERATURE
 It is measured in degrees on the Fahrenheit (ºF) or Celsius (ºC) scales by a
thermometer.
 Temperature varies according to:
 Altitude: temperatures decreases with elevation (temperatures drop by
0, 65 ºC for every 100 m of altitude).
 Latitude: temperatures decrease as you move away from the equator.
Sun rays go directly over the equator areas, so temperatures are higher. In polar
regions are colder because because the Sun´s rays are dispersed over a larger area
of land.
 Distance from the sea: water heats and cool more slowly than the land does;
temperature of the land near large bodies of water is often milder, with no big
variations in temperature.

C. WIND
 Masses of air move around in the atmosphere. This movement causes
wind. There are different types of wind:
 Prevailing winds (vientos predominantes), such as trade winds (vientos alisios)
(Image 2), always blow in the same direction (NE en el hemisferio norte y del
SE en el hemisferio sur) and in the same regions.
 Periodic winds, such as monsoons (Image 1), vary depending on the season
(https://www.youtube.com/watch?v=76dfOmEr4_s)
 Local winds are found in small areas. They usually blow in the same
direction. For example, Tramontana (Islas Baleares), Galerna (Mar
Cantábrico) and Cierzo (Aragón).
Image 2Image 1

D. HUMIDITY AND
PRECIPITATION
 All air masses contain a certain amount of water vapour.
 As a mass of warm air rises, its temperature decreases. The
humidity it contains is transformed into a liquid state and falls
to the Earth’s surface in the form of precipitation.
 There are three main causes of precipitation (page 87):
 Frontal rainfall (lluvias de frente). Image 1
 Storms (lluvias de convección). Image 2
 Relief rainfall (lluvias de relieve/orográficas). Image 3
Image 1 Image 2 Image 3

INTERACTIVE EXERCISES
 WEATHER FORESCAST:
http://repositorio.educa.jccm.es/portal/odes/ingles/weather/cont
enido/contenido/oa05.html
 WEATHER AND CLIMATE:
 WEATHER:

4. THE EARTH´S CLIMATES
 Climatologists divide the Earth into different climate zones.
4.1. THE EARTH´S CLIMATES ZONES.
We can identify three major climates zones: cold, hot and temperate.

COLD ZONES
 Very little sunshine and annual average temperatures are below 0 ºC.
 There are two cold climate zones located within the polar circles:
 One in the Northern Hemisphere, made up of the Arctic Ocean,
Greenland and the northern coasts of Asia, Europe and America.
 One in the Southern Hemisphere, made up of the Antarctic.

HOT ZONES
 There is a single hot climate zone, which is known as the
intertropical zone: It is located between the two tropics.
 The intense sunshine in this region produces annual average
temperatures of above 18 ºC.

TEMPERATE ZONES
 There are two temperate zones: are located between the tropics and the polar
circles.
 Annual average temperatures are between 0 ºC and 18 ºC.
 The amount of sunshine varies throughout the year, resulting in four seasons. In
the Northern hemisphere, the hot season coincides with the summer months. In
the Southern hemisphere, it coincides with the winter months.

4.2. THE EARTH´S CLIMATES TYPES
 Within climates zones there are regions with different types of
climates.
 The combination of annual temperature and precipitation data
results in nine different climate types:
CLIMATE
TYPES
TEMPERATE
CLIMATES
Mediterranean Continental Oceanic
Humid
Subtropical
HOT CLIMATES
Equatorial Tropical Desert
COLD CLIMATES
Polar Alpine

MAP OF THE EARTH´S CLIMATES
TYPES

WHAT IS A CLIMOGRAPH?
 Temperature and precipitation make it possible to identify a
climate.
Both elements can be shown graphically using a
climograph which allows us to observe the annual change
in temperature and precipitation in a specific place on the
planet.
This information is represented using a combination chart
with two systems of coordinates.
 Activity: How to make a climopraph (page 96-97)

Unit 5

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