When we want to know what kind of weather we are having we just go to our phones and find the weather channel. In the old days, following the weather was a bit more fun. They used barometers. My grandparents owned a barometer like this. Every morning I would watch my grandfather thunk the glass and he would turn and tell us that it "looks like a great day for going to the beach" or he would turn around and say, " oh? Looks like rain today, guess we get to stay inside and read". Should have heard my sisters and I groan at that forecast! Barometers measure atmospheric pressure... Atmospheric pressure and barometric pressure is simply the weight of air at ground level. Mr Torricelli discovered that air has weight. If there is more air above you the pressure is greater on you! If you go higher up on a mountain or in an airplane, the air above you is less and there is less pressure on top of you! So...what does barometric pressure or atmospheric pressure have to do with weather? On the weather map we see a large "H" and a large "L". These symbols show where there are massive amounts of air, the H is for high pressure air mass and the L is for low pressure air mass. These masses of air can be hundreds of miles wide. High pressure masses show vertical down drafts of air. The air is cooled and it is dropping down to the ground. When the air warms up again it rises and those air masses show lower pressure as they lift off the ground. When they lift, the air usually condenses and then precipitates bringing rainy weather. These High and Low pressure masses move across the Earth due to winds, the rotation of the Earth and the angle of the Earth compared to its place in space as it revolves around the Sun. That kind of complicates things and weather forecasters try to predict weather the best they can, and using a barometer helps out a whole bunch! Barometers have evolved over the hundreds of years they have been used. And all those years using a barometer has been very handy for those of us who care about the weather....
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Mrs. TaylorI love science! Everything about the world is interesting and never boring. I love to study plants, animals, insects, and people. My favorite subjects are my students who are the most unique organisms on the planet! Categories |