All
over the UK there are weather stations sending in reports
to the Met Office in Exeter every day.
Weather station
A standard weather station will have a
thermometer screen, thermometers, a rain gauge and an anemometer
for measuring wind speed and direction.
Rain gauge
The standard rain gauge is made of copper.
The rain runs into a funnel and into a bottle. The water
is then collected once a day and measured in measuring
cylinder. These are now being replaced by automatic rain
gauges which can record rainfall every minute.
Thermometer screen
This is a white box which is positioned
high off the ground. This is called a Stevenson Screen.
It has special vents to let the air flow freely. Inside
the screen are four thermometers. Two of the thermometers
measure the maximum and minimum thermometers. The other
two are used to record the current air temperature and
the humidity. They are identical but one has the bulb covered
in a white cloth which is kept wet by being dipped in (distilled)
water. These are called 'dry bulb' and 'wet bulb' thermometers.
The difference between these two can be used to measure
the humidity. New thermometers have now been developed
which measure these temperatures electronically and can
display their information on a computer screen.
Campbell-Stokes sunshine recorder
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This looks like a crystal ball. The
glass ball works like a lens and focuses the sun onto
a strip of special card. As the sun moves across the
sky it burns a track into the card to show how many
hours the sun has been shining. This was invented over
100 years ago, but like many pieces of weather equipment
it is now being replaced by automatic electronic devices. |
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Fig 1: Campbell-Stokes sunshine
recorder. |
Radiosondes
Balloons carrying small weather stations
are sent up from stations around the UK at 12 noon and
midnight. They send back to the ground measurements such
as temperature, humidity, wind speed and direction from
high in the atmosphere.
Admiral Beaufort
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The Beaufort wind
scale can be used to measure wind strength. It was
written by Admiral Beaufort who was commander of
HMS Woolwich. He lived from 1774 to 1857.
There are two scales, one for
use on land and one for use at sea. |
| Admiral Beaufort |
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Let's find out
Find a copy of the Beaufort
Scale and make a record of the wind over a period
of two weeks. Try this at different times of the year.
Design your own weather log. You could
do this using a book or a simple computer program.
Ask some grandparents to come in and
talk about what the weather was like when they were younger.
See if they have any photographs, which would give you a
clue as to the weather when they were children.
Things to make
This is a simple barometer.
You will need:
- a small plastic bottle;
- a water tight tray or dish;
- a measure;
- plasticine;
- card;
- scissors;
- pencil.
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Fig 2: A simple home-made barometer. |
Fill the bottle about three quarters full
of water, and also half fill the dish. Put your fingers
over the end and turn the bottle upside down into the tray/dish
of water. Do not remove your fingers until the neck of
the bottle is under the water.
Fix the bottle so that it is standing
upright. Mark the level of water on the side of the bottle.
As the pressure rises and falls so the level of water changes.
Your barometer is one piece of weather equipment that you
can keep inside.
If the air pressure is high, the weather
is usually fine. If it is low then the weather is usually
cloudy and wet.
Amazing facts
Waterspouts are like
tornadoes but they form over water rather than land.
They suck up water and spray from the sea and lakes.
Sometimes they also suck up fish. They can be one
or two kilometres high.
The first weather satellites were
put into orbit in 1960.
One of the driest places on earth
is Arica in Chile (South America), where only 0.76
mm falls every year. A coffee cup would take around
100 years to fill! |
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Fig 3: A waterspout. |
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