Presentaci

1
The thermometer
The thermometer is used to measure the
temperature of the atmosphere. Since the
temperature varies throughout the day, it is
convenient to record the highest and lowest
temperatures during each day. This temperature
data is generally expressed in degrees centigrade
ºC, although in other countries the Fahrenheit
scale is more frequently used.
2
The pluviometer
The pluviometer is used to measure the volume of
precipitation. Each day it is necessary to record
the amount of rain water that has fallen. This
water is collected in a container, and the
rainfall is measured in millimetres. This means
that each millimetre corresponds to a
precipitation of 1 litre per square metre. When
the precipitation has been recorded, the
container is emptied, in order to have it ready
for the following day.
3
The hygrometer
The hygrometer is used to measure atmospheric
humidity. Atmospheric humidity is the amount of
water vapour contained in the air we breathe at a
certain temperature, in relation to the humidity
it could contain (without condensing). Atmospheric
humidity is expressed as a percentage. For
instance, if it is 25 at a temperature of 25
ºC, it means that the air contains, at that
moment, a quarter of the quantity of water vapour
it could have in total at that temperature.
4
The anemometer is a device which is used to
measure the speed of the wind. This is a device
which spins on an axis at a speed which
corresponds to the pressure exerted by the wind
on its metallic pans. The speed of the wind is
expressed in kilometres per hour (km/h).
The anemometer
The weather vane
The weather vane is a meteorological instrument
we use to measure the speed of wind. It consists
of a needle which turns round until the arrow is
pointing in the direction of the wind. It is
often placed on a disc on which the four cardinal
points of the compass are indicated.
5
The barometer
A barometer is an instrument used to measure
atmospheric pressure, that is, the pressure
exerted by the air. The records of atmospheric
pressure in a certain area allow us to establish
which are the high pressure areas (anticyclones)
and which are the low pressure areas.
Activity
Looking at the chart you can see, can you explain
how a barometer works?