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2. What is Weather + Climate
Weather is the hour-by-hour, day-by-day conditions of the
atmosphere.
Climate is the the average weather conditions over a long
period of time.

3. Factors affecting Weather
Temperature
Precipitation
Air pressure
Wind speed and direction
Sunshine
Humidity
Cloud Cover

4. Temperature
Temperature is measured in
degrees centigrade by a
maximum and minimum
thermometer. During the
day, the mercury or alcohol
expands and in the night the
mercury or alcohol
contracts.

5. Precipitation
Rainfall (a type of precipitation) is
measured in mm by a rain gauge.
The water collected can be poured
into a measuring cylinder and then
can be recorded.

6. Air Pressure
Air pressure is measured in
millibars (mb) on a barometer.
As the pressure changes the
cylinder rises causing the
lever to move and the pen to
draw on the rotating drum.

7. Wind Speed
Wind speed is measured in
miles per hour or knots and is
measured using an
anemometer. A wind meter can
also be used.

8. Wind Direction
Wind direction is measured by
a wind vane which turns in the
direction the wind is coming
from. Most of Britain’s winds
come from the south-west.
These are called prevailing
winds.

9. Sunshine
Sunshine is measured
using a Campbell Stokes’
sunshine recorder. A note
is made of how much
sunshine there is everyday.

10. Humidity
Humidity is measured by a
hygrometer in milliliters per cubic
centimeters. However some
hygrometers measure humidity in
percentages.

11. Cloud Cover
Cloud cover is measured in
oktas. Each okta represents
one-eighth of the sky
covered by cloud.

12. Stevenson Screen
A Stevenson Screen is a store
where weather instruments are
kept. It is white to reflect sunlight
and slatted to allow air to
circulate. It is placed on grass
away from buildings and trees.

13. Types of Clouds
Cumulus, Stratus and Stratocumulus
Altocumulus and Altostratus
Cirrocumulus, Cirrus, Cirrostratus and Cumulonimbus

14. The lowest clouds
The lowest clouds in the atmosphere are stratus, cumulus
and stratocumulus. These clouds are around 6,000 feet
high. Stratus clouds are horizontal layers and cumulus
clouds are cotton-like in appearance. Stratocumulus is a
cross between them.

15. Mid-Level Clouds
Mid-level clouds include altocumulus and altostratus.
Theses clouds range from 6,000 feet to 20,000 feet.
Altocumulus clouds are dark individual segments.
Altostratus clouds are thin sheets from which the sun can
be seen through.

16. The Highest Clouds
The highest clouds are cirrus, cirrocumulus, cirrostratus
and cumulonimbus. They are around 20,000 feet high.
Cirrus clouds look like thin wispy stripes, cirrocumulus
clouds look like fish scales, cirrostratus clouds look like
white veils and cumulonimbus clouds are very tall, large
clouds.

17. The Water Cycle
1. The sun causes water to form water vapour and rise up into
the atmosphere. i.e. evaporation.
2. At the same time transpiration (the transfer of water from
trees into the atmosphere) occurs.
3. As water vapour rises it begins to cool. The temperature
falls by 1ºC for every 100m you ascend. At the dew point
the water vapour cools to form clouds.
4. Soon the water droplets become heavy and fall as
precipitation.

18. The Water Cycle Diagram

19. Britain’s Air Masses

20. How do They Affect Us?
Britain receives a lot of rainfall the prevailing winds blow
from the southwest, bringing the tropical maritime air
mass. When the wind blows from the south we receive
the tropical continental air mass, which is dry and comes
from Northern Africa. A northerly or easterly wind in
winter results in snowy conditions generated by the artic
and polar continental air masses. Winds from the north-
west bring the cold weather of the polar maritime air
mass.

21. Factors Affecting UK’s Climate
Latitude
The Gulf Stream
South-westerly Prevailing Winds
Altitude
Distance from the Sea

22. Latitude
The higher the latitude, the colder it will be as the
Sun’s rays have to travel further through the
atmosphere to reach areas of higher latitude like
Britain.

23. The Gulf Stream
The Gulf Stream (North Atlantic Drift) is a water current
from the Gulf of Mexico that brings moist warm air
across the Atlantic Ocean to the west of the British
Isles.

24. SW Prevailing Winds
The south-westerly prevailing winds are the UK’s most
common winds which travel across the Atlantic Ocean
picking up lots of moisture which then gets dropped on
the first land mass it meets - Britain.

25. Altitude
The higher the altitude, the colder it is. Higher areas
like Lake District receive more rainfall because air is
forced to rise upwards and the water vapour condenses
to form clouds.

26. Distance to Sea
Oceans heat up and cool down much more slowly than
land. This means that coastal locations tend to be
cooler in summer and warmer in winter than places
inland which are at the same latitudes and altitudes.

27. Microclimates
Shelter
Surface
Aspect
Natural Physical Features
Buildings

28. Shelter
Buildings, walls, hills and valleys can provide shelter. It
will feel a degree or two warmer on the sheltered side
than the side facing the wind.
This side of the
hedge is warmer. This side is colder as
it is facing the wind.

29. Surface
Dark surfaces absorb heat and are therefore warmer
than light shiny surfaces. Light surfaces reflect heat and
are therefore cooler.
Light surface
reflects heat
Dark surfaces absorb
heat

30. Aspect
As the sun moves through the sky, it warm slopes that
face it. In Britain, south-facing slopes receive more
sunlight than north-facing slopes as the sun moves
through the south during the day.
This slope is
warmer

31. Buildings
During the day, dark buildings absorb heat and release
it in the night. Buildings also break up the wind
depending on the direction they are facing and the
prevailing wind direction.
Buildings absorb
heat.

32. Natural Physical Features
Rain is caught in the canopy of a forest, reducing
precipitation. In winter, it feels warmer in a sheltered
forest as the trees provide protection from the cooling
wind. In summer it feels cooler as the trees block out
the sun.
Warmer in winter and
colder in summer

33. Pressure Systems
Anticyclones
Depressions

34. Anticyclones
Anticyclones
Process Cool air sinking
Air Masses One air mass at time.
Isobars on Map Isobars dispersed
Weather Still or very light winds
Seasonal Variation Very cold in winter; hot in
summer
Pressure High Pressure

35. Depressions
Depression
Process Warm air rising
Air Masses Two air masses
Isobars on Map Isobars tightly packed
Weather Wind, cloudy skies
Seasonal Variation Wet, mild and windy
throughout the year.
Pressure Low pressure

36. Types of Rainfall
Relief Rainfall
Convectional Rainfall
Frontal Rainfall.

37. Relief Rainfall
1. Prevailing winds bring moist air to Britain.
2. Air is forced to rise over high areas.
3. Air cools and condenses
4. Clouds form and it starts to rain.
5. Air descends on the other side of the mountain.
6. It warms up and dries over an area to the east of the
mountains known as the rain shadow.

38. Relief Rainfall Diagram

39. Convectional Rainfall
1. The sun heats the earth.
2. The earth heats the air above it.
3. Hot air rises because it is less dense.
4. The water vapour cools at the dew point and
condenses into water droplets.
5. These water droplets join together and then
fall as rain.

40. Convectional Rainfall Diagram

41. Frontal Rainfall
1. When a warm and cold air mass meet they
don’t mix.
2. The lighter warmer air rises over the heavier,
colder air.
3. As the warm air rises condensation occurs,
clouds form and rain falls along the front.
4. First a warm front passes over, bringing rain
and warm air, then a cold front passes bringing
more rain and cold air.

42. Frontal Rainfall Diagram

43. Layers of the Atmosphere
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere

44. Troposphere
It is the lowest layer of the atmosphere.
Almost all weather occurs in this layer and this is the
layer where planes usually fly.
Starts at Earth’s surface and is around 20km high.
The temperature is about 17ºC

45. Stratosphere
The second layer of the atmosphere is the
stratosphere.
The stratosphere is very dry and so doesn’t contain
many clouds.
The stratosphere extends around 50km down to
anywhere from 6-20km above the Earth surface
The temperature is about -15ºC at the top of the
stratosphere.

46. Mesosphere
This is the third layer of the atmosphere.
Here different gases mix together and meteors
vapourise.
This layer extends from about 50km to 85km above
the earth’s surface.
The temperature is about -90ºC.

47. Thermosphere
This is the fourth layer of atmosphere.
Space shuttles orbit in this layer.
It is about 90km to 5,000km above our planet.
Temperatures can reach 500ºC.

48. Exosphere
This the last layer of our atmosphere.
Here atoms and molecules are released into space.
It is over 5,000km above our planet.
The temperature can reach thousands of Celsius.

49. Thank You For Listening +
Hopefully Watching