# How to Mark a Barometer Gauge

Views: 9906 | Last Update: 2008-07-09
How to Mark a Barometer Gauge - Provided by eHow
A barometer is only as useful as its gauge. Learn how to mark a barometer for measuring air pressure in this free video. View Video Transcript

Gary Zier

## Video Transcript

Hi, I'm Gary for Expert Village. The next thing we do now that we have our jar set up with the air tight seal and the straw attached. And we also have a poster board which will act as our kind of a measuring stick. What we're going to do now is start making marks on the poster board so that we can have indications of the type of weather. So the first thing we do is we go outside and we take the jar and the poster board outside and we make a mark where the straw is pointing. Now that mark over there is going to indicate the type of weather that is outside so we have sunny weather outside and I made a mark next to the poster board where the straw was pointing. And now I'm going to indicate that, that mark is going to represent sunny weather. So next to the mark I'm going to make a picture of the sun and I know that when the jar is next to the poster board and the straw is at that mark, that is the amount of air pressure that's going to indicate sunny weather. Again the way the barometer is working is that the straw is moving according to the pressure against the top of the jar or the pressure against the balloon. So if the air pressure from the outside is greater it's going to press down on the balloon and the straw is going to be tilted upwards. If the air pressure on the inside is stronger than the pressure on the outside then the balloon is going to be raising up and that is going to cause the straw to actually lower and that's going to indicate a different type of weather. So now we see we're going to make marks we have to watch our barometer and as the straw moves its position we have to go and make a mark according, first of all, according to where the straw is pointing to and also according to the type of weather that exists outside. And after we watch the barometer for a few hours and over the period even over a few days we're going to have an indication we're going to be making a series of markings on the poster board and then we'll have accurate measures of the different types of weather outside and we can see as the barometer is getting lower or higher if it's in depending on which direction it's starting to move we can in some type of accuracy even predict the weather. We can know when to expect rain or when to expect a sunny day.