 |
| Barometer |
A barometer tells us what the weather may be like by measuring
changes in air pressure.A barometer is an instrument that measure the pressure of air.
The ocean of air above us pushes down on the earth with a great
deal of force. Just as a scale measures
the pressure of your weight, so the barometer tells the weight of the air above
it.There are different kinds of barometers.
Barometers called “aneroid barometers” record changes in air
pressure by using an air light box from which most of the air has been removed.
Changes in air pressure causes the box to expand or contract. These changes controls a pointer on a dial.
When we read a mercury barometer, we read the height of mercury in
a glass tube. Changes in air pressure
causes the mercury to rise or fall.
Barometer are very useful to the weatherman.
When the mercury falls rapidly, he knows a storm is quite likely
to follow. A “rising barometer” often
foretells better weather – Dick Rogers
No comments:
Post a Comment