how do you set a barometer?

Answer 1

If you have your own homemade one in order for it to work you need a vacuum to vacuum out the air so the mercury will expand and contrast.

Answer 2

Long time since I had anything to do with barometers.
I have never had to calibrate one, it was used to check efficiency of a power plant mainly, and not really used with any real accuracy, so to get a really accurate barometric reading I had to pone the nearest airport.
The barometer you have at home a has sort of 'set point' on the dial this is usually pre set to show you the average reading in your given area, for your purposes it doesn't have to be accurate, you are just using the gadget to observe if the atmospheric pressure is rising or falling against a 'norm' so you can check if there is going to be a change in the weather.
So you could have your 'norm' for your area set at 200 bananas, if the actual reading is 10 bananas above or below that norm you can work out what the weather is likely to be, you could be expecting a banana storm!!

Answer 3

For any increase in altitude there is a corresponding decrease in atmospheric pressure. Barometric pressures given by weather reports are for sea level (0 ft/m). If a barometer is moved to a higher or lower location, the pressure will change. This means that a compensation will have to be made.
An aneroid barometer is adjusted by means of a screw in the back. The easiest way to find the correct setting is to use the link at the bottom of this page. Follow the instructions to get the weather for your area, & you will find the current barometer reading for your nearest airport or weather center. You can then set it to this (as the pressure given is for sea level).
The adjustment of a wheel barometer should be left to an expert. (You should ask for it to be set for the correct altitude when bought -you may be charged).
A stick barometer is designed to give the correct pressure when at sea level and a manual compensation will have to be made. (See also how a stick barometer works, above).

Fortin barometers have to be set before each reading is taken. Using the screw at the bottom adjust the mercury level, seen in the glass reservoir, until it is just below the pointer(called the fiducial point), then re-adjust it until the surface just touches the tip. The barometer is then ready for a reading to be taken.
The table below sets out the corrections (in inches)required. Should you live below sea level then subtract 0.06" per 50 ft (15m). To convert the corrections to mm mercury multiply by 25.4 & to millibars by 33.86

Answer 4

There are two types of mercury barometers.One is Fortin's barometer and the other is Kew Pattern barometer.In Fortin's barometer the mercury cistern(mercury container) is a movable one and in the other one the cistern is a fixed one.
So, in the Fortin's barometer, double setting has to be done.The cistern shoud be moved up and down with a screw, to touch a pointer at the bottom of the tube and again the sliding vernier scale should be adjusted with another screw to read the reading.
In the Kew pattern barometer , the cistern is fixed and need not be adjusted.Only the vernier scale should be adjusted with a screw to read the value.

Answer 5

As far as I know you don't set a barometer. However, there is a pointer that you can set to see if it is rising or falling.

Oh, did I mention that all of this depends on it being a real barometer not an electronic one...if it is electronic I can't help you.

Russ

Answer 6

You need to contact the meteorological office, give your address and postcode, and they will ascertain your location's height above sea level. Only when this has been established will your barometer give a true reading.

Answer 7

There is normally a small screw on the back where you can set the needle. You can get the barometric pressure fro good weather reports

http://www.bbc.co.uk/weather/features/setting_barometer.shtml

Answer 8

the weather thing?

u don't normally , i'm sure they are sealed vacumed units..

they work of the pressure in the atmosphere.