Weather Instruments

Question 1

How does a thermometer work?

Answer 1

During the day the alcohol in the thermometer heats up and expands, pushing the mercury higher on the maximum scale. At night the alcohol cools down and contracts so the mercury reads lower on the minimum scale. In each case the position of the extreme temperature is recorded by a pin. The pins have to be drawn back (reset) yo the mercury each day using a magnet.
(When a liquid warms up it expands in volume moving up the tube of the thermometer. When the liquid cools it decreases in volume going down the tube)

Question 2

How does a rain gauge work?

Answer 2

A rain gauge is a metal cylinder which contains a collecting bottle and a funnel. It is partly sunk into the ground for stability in the wind, away from trees and buildings which would shelter it and the rim is 30mm above ground level to avoid splashing. The rainwater is transferred to a measuring glass and recorded in mm.

Question 3

How does a wet and dry bulb thermometer work?

Answer 3

The wet bulb thermometer gives the temperature at which moisture in the air will condense. This is the dew point temperature. The dry bulb thermometer shows the actual temperature of the air. If the two temperatures are close the air is humid.

Question 4

What is the average air pressure?

Answer 4

1013.2 hPa

Question 5

What does high pressure indicate in terms of weather conditions?

Answer 5

Calm, dry, stable weather

Question 6

What does low pressure indicate in terms of weather conditions?

Answer 6

Rain, clouds, wind, unstable weather

Question 7

How does a barograph work?

Answer 7

The metal cylinder contains a vacuum. Attached to it is a level and a pen. The pen records onto the graph paper attached to a rotating drum. As air pressure increases, or decreases, the cylinder is pressed downwards (or rises) raising (or lowering) the lever and pen.

Question 8

How does an anemometer work?

Answer 8

.Cups which rotate as wind blows into them
.Meter recording the speed

Question 9

How does a wind vane work?

Answer 9

The wind blows the wind vane causing it to turn. There are compass points attached to the pole. The pointer spins in the wind and points in the direction of the compass points (explain better. Im sorry)

Question 10

How does a sunshine recorder work?

Answer 10

The glass ball focuses the sun’s rays onto graph paper behind it, and burns the paper. You can then calculate how many hours the sun shone that day by reading the length of the burn(s) on the paper