Challenge of weather and climate
1. What is the climate of the UK?
Key Terms
Climate: the average weather conditions recorded over a period of at
least 30 years.
Weather: the day-to-day conditions of the atmosphere involving, for
example, a description of cloud cover, temperature and wind direction.
Convectional rainfall: intense rainfall often in the form of thunderstorms
resulting from very high temperatures and rapidly rising and cooling air.
Relief Rainfall: Rain caused by warm, moist air being forced to rise
usually by high land eg. Mountains. The air then cools as it rises, forms
cloud and rains.
North Atlantic Drift: a warm ocean current from the South Atlantic
which brings warm conditions to the west coast of the UK.
Prevailing Winds: the dominant (main) wind direction.
Maritime influence: the influence of the sea on climate.
Continentality: the influence of being close to or far away from the sea.
Inland areas well away from the coast have a continental climate.
Insolation: energy from the sun used to heat up the Earth’s surface.
Difference between weather and climate
Weather is the day-to-day conditions of the atmosphere eg.
Temperature, wind direction, cloud cover, amount of rain. Climate is the
average weather conditions over at least 30 years.
Therefore weather looks at the short term, while Climate looks at the
long term conditions in the atmosphere.
The climate of the UK has a lot to do with its location.
 It is at a battleground where Warm Tropical air meets Cold Polar
air. These different air masses battle for control over the area
the UK is in – the mid Latitudes. The UK experiences very
changeable weather because of these air masses, large bodies of
air.
 Due to our high northernly position we get less heat energy from
the sun than those places at the equator. In summer the sun is high
in the sky so there is a lot of potential warm sunshine. In winter
the low angle of the sun means there is less sun and lower
temperatures.
Weather
Weather looks at how the
atmosphere changes. It looks at:
Temperature – how hot or cold
Cloud cover – amount of cloud in
the sky.
Humidity – amount of moisture in
the air
Wind speed – how powerful the
wind is.
Wind direction – the direction the
wind comes from
Precipitation – amount of rain, hail,
sleet or snow.
Sunshine – how many hours of sun
you get a day.
How do we measure the weather?
Temperature by a Thermometer.
Precipitation by a Rain gauge.
Sunshine by a sunshine recorder.
Wind speed by an Anometer.
Wind direction by a wind vane.
Air pressure by a Barometer.
AIRMASSES
Air masses are large bodies of air. Where they come from can
tell us the weather they will bring.
Tm -Tropical Maritime (S.W.)
The surface of this warm air becomes cooled as it moves north so mist or
fog forms or, if the air is lifted, it will form low banks of Stratus
Cloud.
In the higher air Fair Weather Cumulus Clouds form. Weather is dry.
Pm – Polar Maritime (N.W.)
As this cold air moves south it picks up moisture and this warmer air rises
quickly to form tall cumulo-nimbus clouds producing heavy showers of
rain or snow.
The showers are particularly frequent and heavy over the mountains.
Tc – Tropical Continental (S.E.)
Air from North Africa (unusual) brings hot, dry air.
Gives clear skies and sunny days.
Pc – Polar Continental (N.E. or E)
Well broken cloud, fine and sunny weather but very cold. If it passes over
the sea it may bring some drizzle or snow to eastern coastal districts.
Factors affecting our climate
The following factors affect our climate:
 Latitude
 Ocean Currents (North Atlantic Drift)
 Prevailing winds
 Maritime influence
 Continentality
 Altitude
(Draw diagram A P54)
Latitude
Latitude is the distance from the equator. The position on the globe
affects your climate. If you are near the equator (the dividing line
halfway down the Earth) the suns rays hit the Earth straight on, have a
small area to heat, in planetary terms, and this gives high temperatures.
In the UK we are far north. The suns rays hit the Earth at an angle. This
means the suns rays hit the Earth at an angle. This means they must heat
up a larger part of the Earth’s surface. This leads to lower temperatures.
(Draw diagram of Latitude)
Ocean Currents
A warm ocean current from Mexico and the Carribbean, called the North
Atlantic Drift, brings warm water and air to the UK. This makes our
weather damp and milder than it should be. We should be as cold as
Alaska or Moscow which have the same Latitude.
Prevailing winds
This means what direction our winds usually come from. In the UK our
winds come from the south-west. The winds mainly come from a warm
ocean giving us relatively mild but damp climate.
Maritime influence
Our closeness to the sea affects our climate. We live on an island and the
air above us is humid (wet) as a result. This explains the often high
amounts of rainfall and cloudy weather we get.
Continentality
Areas further away from the sea, inland, tend to be drier than beside it.
In summer the suns rays heat up land quicker than the sea. So in summer
the land gets hot quickly but the sea is still cold.
In the winter the land loses heat more quickly but the seas keep their
heat longer. The further inland you are the colder your winters.
(Draw diagram)
Types of Rainfall
There are three types of Rainfall.
 Convectional Rainfall
(Draw diagram)

Relief Rainfall
(Draw diagram)
(Write explanation of how it is caused)
 Frontal Rainfall
It is caused by the meeting of cold and warm air at fronts.
(See Depressions)
Climate Characteristics in the UK
 January Temperature
 July Temperature
 Precipitation
 Sunshine
(Write a description for each climate map in Figure C P55. )
(Do Activity 1, 2a and 2b)
2. What causes the weather in the UK?
Key Terms
Depression: an area of low atmospheric pressure.
Front: a boundary between warm and cold air.
Warm Front: a boundary with cold air ahead of warm air.
Warm sector: an area of warm air between a warm front and a cold front.
Cold Front: a boundary with warm air ahead of cold air.
Occluded Front: a front formed when the cold front catches up with the
warm front.
Anticyclone: an area of high atmospheric pressure.
Frost: results from the temperature of the ground or of the air, dropping
below 0°C.
Fog: water that has condensed close to the ground to form a dense low
cloud with poor visibility.
What is pressure?
Pressure is the weight of air pressing down on the earth's surface.
Pressure varies from place to place and results in pressure systems.
Low pressure often brings wet, windy weather.
High pressure often brings clear skies, little wind with heat waves and
high temperatures in summer, very cold temperatures in winter.
How is pressure shown?
Pressure is shown on maps as Isobars.
Isobars are lines on a weather map joining together places of equal
atmospheric pressure.
Note that:
 The numbers measure the atmospheric pressure in millibars.

Usually isobars are drawn at intervals of two or four millibars
(one thousandth of a bar).

The closer the isobars are together the windier it is.

If the lowest number is in the middle circle this is a low
pressure or depression. Often low pressures mean wet and
windy weather.

If the highest number is in the middle circle, this is a high
pressure or anticyclone. Often high pressures mean dry, sunny
weather.

Air pressure tends to range from 890mb (a hurricane) to
1060mb (an anticyclone).
(Draw pictures of high and low pressure)
Definition of a depression
A depression is an area of low atmospheric pressure. In a depression
air is rising and this leads to clouds forming and rain.
In the UK and Ireland most of weather is caused by the passing of
depressions.
They usually form over the Atlantic Ocean, pass across the UK from
west to east driven by the prevailing winds.
Winds in a depression go round in an anti-clockwise direction.
(Draw a depression as shown on a weather map with the direction of
the winds marked on)
What are fronts?
(Draw a warm front, a cold front and an Occluded Front)
The boundary between warm and cold air are called fronts (just like
WW2 – DIFFERENT ARMIES).
The warm front marks an area of warmer air.
The cold front marks an area of colder air.
At fronts air is forced to rise, often forming bands of cloud and rain.
Over time the Cold front will catch up with a warm front leading to a
single boundary called an Occluded Front. This will eventually see the
depression fizzle out and die.
The Formation and development of depressions
(Draw Diagram A p57)
(Draw image and label it for Satellite Image B p57)
Weather Maps and Synoptic Charts
(Do Separate question sheet on weather maps and synoptic charts)
(Do All activities on p59)

Learn diagram E on page 58.
Answer the following questions.
1. Write down a full description of the weather for each of the 6
weather stations in Diagram D p58.
2. As the depression passes describe how the weather changes
(mention 3 weather stations).
3. Look at the Isobars in Fig D p58. What is the lowest pressure?
4. Complete this sentence. Pressure goes up or down in
_____________.
Weather associated with a depression
A depression is divided into 3 sets of weather:
1. Weather ahead of the warm front
2. Weather in the warm sector
3. Weather at and behind the Cold Front.
(Write down a description of the weather at each of these 3 places using
p58).
Cross section through a depression
(Draw diagram on p59)
Copy Table of weather associated with the passage of a depression, p59.
(Q 1, 2, 3 ON PAGE 59)
The Characteristics of anticyclones
 Anticyclones are areas of high atmospheric pressure.
 They are caused by air sinking towards the ground
surface.
 The sinking air stops areas of air rising.
 Rainfall unlikely.
 Most of the time it will clear and sunny.
 Winds in the northern hemisphere go round in a clockwise
direction.
(Draw a Satellite image of an Anti-cyclone – mark on the direction of
the winds)
In winter
 Clear, cloudless conditions.
 Sunny and crisp days.
 At night, heat lost rapidly due to absence of a blanket of
cloud.
 This leads to frosty nights.
 Surrounded by sea, the air over the UK is often moist.
 Under cold conditions the moist air readily condenses to
form low cloud and fog.
 These overcast conditions (known as ‘anticyclonic gloom’ )
can last for several days at a time.
 It can see plants die due to frosty conditions and black
ice on the roads.
In Summer
 Sun more powerful and can burn off any low cloud and
fog.
 This leads to warm and sunny days.
 Can lead to ‘heat waves’ long spell of very warm weather.
 Can lead to melting tarmac, glare on windscreens making
driving problematic.
(Do a table comparing Weather in a Winter and Summer anti-cyclone. Use
the following headings:





Wind direction
Wind strength
Cloud cover
Temperature
Type of weather)
Q1. How does cloud affect temperatures in winter?
Q2. In a Winter anti-cyclone how does the absence of cloud affect
temperatures?
Case Study: Winter anticyclone 2 February 2006
At the end of January and into the start of February 2006, a large anticyclone became established over the UK.
It contained a great deal of moisture with low temperatures and little
wind (Isobars far apart) – this gave dull, overcast (complete cloud cover)
conditions with mist and fog.
If the air had been drier continental air, conditions would have been
different with cold, crisp and sunny days and frosty nights.
(Draw simple satellite image of Winter Anti-cyclone, p60)
Case Study: Summer anticyclone 24 July 2008
In mid-July 2008 an anticyclone settled to the east of the UK.
With air circulating around the anti-cyclone in a clockwise direction, this
introduced warm easterly to much of the UK.




There is very little cloud in the centre of the anti-cyclone. This is
because air is sinking, suppressing cloud formation.
There is more cloud at the edge of the anti-cyclone where
conditions are slightly less settled. This accounts for the cloudier
weather in south-west England and Wales.
The lack of cloud in the summer accounts for the high
temperatures in much of the UK.
Although the easterly winds have brought warm and dry air to
much of southern England, note that it is cooler and cloudier over
parts of the north-east coast. This is because the wind has
travelled over the cooler and wetter North Sea.
(Draw simple weather chart of summer anti-cyclone, p61)
(Do Activity 4 and 5b,c,d,e on page 61)
3. Is the weather in the UK becoming more
extreme?
Key words
Extreme weather: a weather event such as a flash flood or severe
snowstorm that is significantly different from the average.
Global warming: an increase in world temperature as a result of the
increase in greenhouse gases (carbon dioxide, methane, CFCs and nitrous
oxide) in the atmosphere brought about by the burning of fossil fuels, for
example.
Extreme weather events
Links to Global warming
Case Study: The Boscastle Flash Flood, 2004
What happened?
Effects
Planning for the Future
4. What is the evidence for Global
Warming?
Key words
Pleistocene Period: a geological time period lasting from about 2 million
years ago until 10,000 years ago. Sometimes this period is referred to as
the Ice Age.
Global Warming: the recent trend showing an increase in global
temperatures.
Greenhouse effect: the blanketing effect of the atmosphere in retaining
heat given off from the earth’s surface.
Greenhouse gases: gases such as carbon dioxide and methane, which are
effective at absorbing heat given off from the earth.
History
Assessing the evidence for Global Warming
Instrument readings
Glacier retreat
Arctic ice cover
Ice cores
Early Spring
Causes of Climate change and global warming
Greenhouse effect
Greenhouse gases and their sources
Human activities and Global Warming
5. What are the possible effects of global
warming?
Map – Possible impacts of Global warming in the UK
Impacts of Global Warming in the UK
Impacts of Global warming in the World
Advantages and disadvantages of Global Warming
6. What are the responses to global
warming?
Key Terms
Recycling: using material, such as aluminium or glass, time and again.
Congestion Charging: charging vehicles to enter cities, with the aim of
reducing the use of vehicles.
Kyoto Protocol: an international agreement aimed at reducing carbon
emissions from industrialised countries.
Carbon Credits: a means of trading carbon between organisations or
countries in order to meet an overall target.
Individual and local responses
National responses
International responses
Table of Individual, national and International responses
7. What is the Hurricane Hazard?
Key Terms
Hurricane: a powerful tropical storm with sustained winds of over 120
kph (75mph). Also known as tropical cyclone, a cyclone or a typhoon.
Eye: the centre of a hurricane where sinking air creates clear conditions.
Eye wall: a high bank of cloud either side of the eye where wind speeds
are high and heavy rainfalls.
Track: the path or course of a hurricane.
How are Hurricanes formed?
Location of Hurricanes
The structure of a Hurricane
The effects of hurricanes
Reducing the Hurricane Hazard
Comparison of Hurricanes in MEDC and LEDC FORECASTING
WEATHER
1.Where do forecasters get their weather information from?
a).Synoptic Charts
 Weather stations on land
 Weather ships at sea
 Passing ships and aircraft.
THE
Radiosondes sent up into the atmosphere (balloons with
instruments attached)
This information is collated at Bracknell Headquarters and Synoptic
Charts are produced to show this information and weather forecasts can
therefore be made.

b).Satellite Images
There are a number of satellites stationed over the Atlantic Ocean and
their satellite images help to show weather patterns, especially the
passage of depressions.
2.Range of a forecast.
The most accurate forecasts can be made for a 24 - hour period. The
general pattern can be given for a weekly period. The longer the range of
a forecast then the more uncertain it can be as weather systems can
change direction quickly.
3.Who uses weather Forecasts?
Many groups of people value accurate weather forecasts as the weather
directly affects their activities and allows them to make plans to suit the
weather.
 Air Traffic Control/Airports. Frost, snow, strength and direction
of the wind can all affect whether aircraft can take off or land.
 Shipping and Ferry Companies. Strong winds affect sailings.