This document discusses the atmosphere and factors that influence climate and weather. It covers the layers of the atmosphere, temperature variations based on altitude and latitude, different types of precipitation and what influences precipitation amounts. It also discusses atmospheric pressure and winds, how weather maps work, and how human activities like air pollution and greenhouse gas emissions can impact climate through global warming and climate change.

1. UNIT 4.

2. Index
1. The atmosphere
a) The layers of the atmosphere
b) Climate and weather
2. Temperature
a) Factors which influence temperature
b) Climate zones
3. Precipitation
a) What causes precipitation?
b) Factors affecting precipitation
4. Atmospheric pressure and wind
a) Atmospheric pressure
b) Wind
c) Weather maps
5. Climate and human activity:
a) Air pollution
b) Global warming and climate change

3. 1. The atmosphere.
A) The layers of the atmosphere:
 Atmosphere:
 Is a layer of gases surrounding the Earth up to an altitude of more tan
1.000km.
 It regulates the Earth’s temperature and allows heat to circulate from warm
to cold regions.
B) Climate and weather:
Weather and climate are related to things like temperature, precipitation,
atmospheric pressure and wind:
 Climate:
 Is the typical state of the atmosphere in a region over a long period of time.
 E.g: Summers are hot in Spain.
 Weather:
 Is the state of the atmosphere in a specific place and time
 E.g:It is snowing in Burgos today.

4. 2.Temperature:
A. Factors which influence temperature:
 Temperature: is the amount of heat in the atmosphere.
 We measured temperatures with a termometer and the unit of
measurement is degrees centigrade (0C).
 Isotherms: on a map are the lines that join areas with the same
temperature.
Temperatures vary according to:
a) Altitude: Temperatures are usually warmest at low
altitudes and get colder as we go higher.
b) Distance from the sea: The sea moderates temperatures:
coastal areas are milder than inland areas.
c) Latitude. Temperatures vary with latitude: they are highest near the
equator and lowest near the poles.
Inland : away from the coast.

5. 2.Temperature:
B. Climate zones:
 The Earth is divided into five main climate zones:

6. 3.Precipitation:
A. What causes precipitation?:
 Precipitation can be rain, snow or hail. It is part of the water
cycle.
 We measure the amount of rain using a rain gauge or
pluviometer.
 The unit of measurement is milimmeters (mm) or litres per
square metre (l/m2).
B. Factors affecting precipitation:
 There are different amounts of precipitation in different parts
of the Earth’s surface. It depending on:
① Latitude: more rain in regions near the Equator, because
temperatures are higher, water evaporates rapidly and falls as
rain.
② Altitude: it rains more in the mountains.
③ Humidity: it rains more on the coast than inland, because
Oceans and seas are a source of humidity.

7. 3.Precipitation:
C. Types of rainfall:
① Orografic or relief rainfall: is found in mountainous regions.
② Frontal rainfall: occurs at the front (or boundary) between a
mass of warm air and a mass of cold air.
1) Convectional rainfall: is found
in hot and temperate climates.

8. 3.Precipitation:
C. Types of rainfall:
2) Orografic or relief rainfall: is
found in mountainous regions.
3) Frontal rainfall:
occurs at the front (or
boundary) between a
mass of warm air and a
mass of cold air.

10. 4.Atmospheric pressure and wind:
A. Atmospheric pressure:
 Atmospheric pressure is the weight of the air above the Earth’s
surface.
 We measure atmospheric pressure with a barometer.
 The units of measurement are milibars (mb)
Atmospheric pressure varies according to altitude and temperature:
 Altitude: atmospheric pressure is lower in high, mountainous areas.
 Temperature: hot air weighs less than cold air.
Atmospheric conditions are affected by pressure:
 Anticyclones are areas of high pressure. They cause dry, stable
weather and clear skies.
 Depressions are areas of low pressure. They cause unstable weather,
rain and storms.

12. 4.Atmospheric pressure and wind:
B. Wind:
 Is a mass of moving air. It is caused by differences in atmospheric
pressure. Air always goes from areas of high pressure to areas of low
pressure.
 Wind speed is measure with an anemometer.
 The unit of measurement is kilometres per hour (km/h).
 Wind direction is measures using a weather vane.
Types of wind:
 Prevailing winds blow in the same direction
(trade winds: from the tropics to the equator).

13. 4.Atmospheric pressure and wind:
B. Wind:
Types of wind:
 Seasonal winds change direction according to the season (monsoon
in Asia: from the Indian Ocean to the continent in summer, carrying
rain).
 Daily pattern: change direction on a daily basis (sea breeze blows
from the sea to the land during the day and then, the direction
changes and a land brezee blows from the land to the sea at night).

14. 4.Atmospheric pressure and wind:
C. Weather maps:
 It shows atmospheric pressure at sea level.
 Features of a weather map:
• Isobars: lines that connect areas with the same atmospheric pressure.
• H/A: high pressure area (anticyclone). Weather stable and dry.
• L/B: low pressure area (depression). Storms and rain.
• Blue lines: clod fronts. Unstable weather.
• Red lines: warm fronts. Unstable weather.
A front is a line of separation
between warm and cold air
masses. It resulting in stormy
weather.

15. 4.Atmospheric pressure and wind:
C. Weather maps:

16. 5.Climate and human activity:
A. Air pollution:
 Is the contamination of the atmosphere caused by human activities
(manufacturing industries, transport, agricultura, etc.).
 Harmful gases, smoke and dust accumulate in the air.
 It causes health problems.
 It causes harm to the environment:
o The Greenhouse effect is a natural process that prevents solar heat
from leaving Earth’s Surface. However, the concentration of carbon
dioxide released by human activities makes this effect stronger.
Consequently, the temperaturas are rising at the Earth’s surface.
o Acid rain: rain wáter cmbines with harmful gases, and fall as acid
rain. This is harmful to plants and animals.
o The depletion of the ozone layer: this layer protects the Earth from
the Sun’s ultraviolet rays

17. 5.Climate and human activity:
B. Global warming and climate change:
 Global warming: is the increase of average temperaturas on Earth’s
surface.
 Consecuences:
 Climate change
 Melting of the polar ice caps.
 Scientists says it is crucial to reduce the emission of greenhouse
gases (as CO2).