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Global Distributions of Climate The climate in a
place is the average of its weather
conditions. The climate varies across the world
depending on the following four
factors Latitude Altitude Distance from the
sea Prevailing winds
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Latitude The closer an area is to the equator,
the hotter the area will be. This is because the
direct rays from the sun are concentrated along
the equator. Altitude Temperature decreases the
higher we travel into the atmosphere. The higher
a place is above the sea level, the colder it is
likely to be. Distance from the sea In the
summer, the sea heats up less quickly than the
land so places further inland will have hotter
summers. In the winter, the sea heats up more
quickly than the land so people on the coast will
have warmer winters. Prevailing winds If the wind
blows from the direction of the equator, then it
is likely to be warm. If the wind blows from
either of the poles then it is likely to be cold.
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Climate Zones There are six major climate zones
located throughout the world. Equatorial Lying
between the Tropic of Cancer in the Northern
Hemisphere and the Tropic of Capricorn in the
south, equatorial climates are home to most of
the worlds rainforests where rainfall and
humidity are high. Temperatures are not that
extreme generally 25 to 35 C with not much
variation through the year. Arid Deserts are
found mainly across the subtropical continents.
Here, descending air forms large, almost
permanent, areas of high pressure leading to
cloud-free skies virtually all year round. Annual
rainfall is low and, in some deserts, almost
non-existent. Because theyre so dry, the
temperature range in deserts is huge, regularly
exceeding 45 C by day in summer and often
falling to below freezing overnight in
winter. Mediterranean The hot, dry summers of
the Mediterranean, South Africa and southern
Australia are caused by a seasonal shift of the
descending air that also creates our deserts. Low
summer rainfall is matched by many months of
warm, sunny weather. But, at times, dangerously
hot spells of weather engulf these regions with
fiercely high temperatures of up to 45 C. In
winter, there is more rain and cooler
temperatures, but little frost. This
classification covers a range of climates from
Mediterranean-type climates and humid,
subtropical zones to maritime climates influenced
by the oceans
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Snow In the higher northern latitudes, the vast
forests of fir and spruce (often called the
taiga) and the featureless tundra endure long,
hard winters with short, bountiful summers,
separated by rapid seasonal changes during spring
and autumn. In the northernmost regions, the land
is permanently frozen and will not thaw even
during the brief summer. Polar The Arctic is
mostly frozen ocean, and while its climate is
moderated by the relatively warm waters of the
Atlantic Ocean, winter temperatures can still
fall to below -30 C. Antarctica is a vast
continent of mountains and high plateaux buried
under more than 3 km of ice. Temperatures below
-80 C have been recorded and the Antarctic i
nterior is very dry drier than many deserts.
This is because as the temperature falls so does
the atmospheres capacity to hold water vapour
needed to make snow. Temperate This
classification covers a range of climates from
Mediterranean-type climates and humid,
subtropical zones to maritime climates influenced
by the oceans like ours in the UK. The UK has a
typical maritime climate, where temperatures are
quite moderate although hot summer days and cold
winter nights still occur. Summers in maritime
climates can be hot, warm or cool. In the UK we
have whats considered to be a warm summer,
whereas in Iceland the season is classified as
cool.
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How to measure weather?

• Meteorological Stations collect many different
  types of data.
• Specific instruments are used to collect this
  information

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Types of Data

• Temperature (C)
• Daily Maximum and Minimum Temperature (C)
• Pressure (mb millibar)
• Wind direction
• Wind Speed (km/h)
• Rainfall (mm)
• Relative humidity ()

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Data Collection

• Stevenson Screen
• A device that contains instruments that record
  certain weather data
• Technical details
• Double louvered sides for air circulation
• 1,25m above ground
• Double roof, air insulates against sun
• Painted white, to reflect sun / heat
• Located in open space, to reduce interfrerence
  form buildings / trees
• Door opens north in northern hemisphere / south
  in southern hemisphere to avoid sun shining on
  instruments

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Inside a Stevenson Screen

• Minimum / Maximum Thermometer
• Wet / Dry bulb thermometer
• Barometer

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Maxi / Min Thermometer

• Filled with Mercury or Alcohol
• U-shaped capillary tube, min side bulb filled
  with liquid, other with vacuum
• 2 separate temperature readings
• Steel markers show temperature (can be reset by
  magnet)
• Heating ? expansion
• Cooling ? contraction
• Use recoding of daily temperature maxima

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Wet / Dry Bulb Thermometer

• Aka Hygrometers
• 1 normal thermometer
• 1 wet thermometer
• Wet one shows temperature at 100 humidity
• Use The difference between dry and wet
  temperature can be used to calculate relative
  humidity

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Barometer

• Measures atmospheric pressure
• Average 1013,25 mb
• Mercury Barometer
• Changes in air pressure push mercury up the tube
• Aneroid Barometer
• Changing pressure causes expansion and
  contraction of vacuum container

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Rain Gauge

• Collects water to determine how much rain falls
• Collection either daily or hourly
• Location
• Located away from buildings to reduce shelter
  effect
• Top must be 30cm from ground to avoid splatter
  from ground
• Base sunk into ground to avoid tripping
• Needs collecting funnel
• Narrow opening to avoid loss through evaporation

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Wind vanes

• Wind vanes
• Show wind direction
• Results can shown on a circular graph (wind rose)

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Anemometers

• Record the speed of wind
• Speed is recoded in km/h or knots
• 1knot 1,852km/h
• 10knots 1 barb
• Location
• In the open
• On a high pole

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Cloud Cover

• Measures how much of the sky is covered by clouds
• Measurement in Oktas
• 1 Okta 1/8th of the sky 12,5
  of the sky

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Cloud types

• Alto high
• Cirrus lock of hair
• Cumulus heap
• Nimbus precipitation bearing
• Stratus layer

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Cloud types

• High level
• Cirrus above 6000m, composed of ice crystals
• Mid level
• Altostratus formation due to rising air,
  condensation, can bring rain/snow
• Low level
• Nimbostratus dark grey, brings persistant rain
  low visibility, formless cloud layer
• Stratocumulus large, lumpy layered clouds,
  produce rain / drizzle
• Stratus continuous horizontal layer and level
  base, can produce drizzle
• Cumulus puffy small clouds, fai weather clouds
• Cumulonimbus large, dense and very tall,
  invovled in thunderstorms and intense weather

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Clouds
Cirrus
Cumulus
Altostratus
Nimbostratus
Stratocumulus
Stratus
Cumulonimbus
mammatus
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Summary Meteorological Data

• Stevenson Screen
• Contains Min / Max thtermometer, Wet / Dry bulb
  thermometer, Barometer
• Measures Daily Min and Maximum temperature, Data
  for Relative humidity collection, atmospheric
  pressure
• Open space observation
• Rain gauge measures daily or hourly rainfall
• Wind vane measures wind direction
• Anemometer measures wind speed
• Cloud cover measures the amount of clouds,
  records type of cloud

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Weather is...

• the day to day condition of the air around us
  over a short period of time.

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Temperature

• Temperature means how hot or cold it is
• It is usually measured with a thermometer in
  degrees centigrade(ºC)

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Pressure

• Pressure is a measure of how heavy the air is.
• Pressure is measured with a barometer in
  millibars (mb)

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Cloud Cover

• Cloud Cover tells us how much of the sky is
  covered by clouds.
• It is measured by estimating the amount of cloud
  cover in eighths.

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Wind Speed

• Wind speed is how fast the wind is blowing.
• An anemometer measures wind speed in mph.
• The most common type looks like a toy windmill.
  Three cups are fixed to a central shaft and the
  stronger the wind blows the faster they spin
  around. The wind speed is shown on a dial, just
  like a car's speedometer

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Wind Direction

• Wind direction is where the wind is blowing from.
• Wind Vane/Wind Sock measures wind direction by
  pointing towards North, East, South or West

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Rainfall/Precipitation

• Precipitation is water falling from the sky.
• Rain gauge measures the amount of rainfall in
  mm. Not only does a rain gauge measure rainfall,
  but also all other forms of precipitation.

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Sunshine

• Sunshine is light and warmth from the sun.
• A Campbell Stokes Recorder measures sunshine.
• This type of recorder is made up of a glass ball
  which concentrates sunshine on to a thick piece
  of card. The sunshine then burns a mark on the
  card which shows the number of hours of sunshine
  in the day.

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Visibility

• Visibility is how far ahead we can see.
• It is measured using a tape measure or trundle
  wheel, in metres or kilometres.