Why do we measure atmospheric pressure

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You cannot download interactives. Weather is the state of the atmosphere, including temperature, atmospheric pressure, wind, humidity, precipitation, and cloud cover. It differs from climate, which is all weather conditions for a particular location averaged over about 30 years. Weather is influenced by latitude, altitude, and local and regional geography. It impacts the way people dress each day and the types of structures built.

Explore weather and its impacts with this curated collection of classroom resources. An atmosphere is the layers of gases surrounding a planet or other celestial body. These gases are found in layers troposphere, stratosphere, mesosphere, thermosphere, and exosphere defined by unique features such as temperature and pressure.

The atmosphere protects life on earth by shielding it from incoming ultraviolet UV radiation, keeping the planet warm through insulation, and preventing extremes between day and night temperatures. The sun heats layers of the atmosphere causing it to convect driving air movement and weather patterns around the world.

Teach your students about the Earth's atmosphere with the resources in this collection. A barometer is a tool used to measure atmospheric pressure, also called barometric pressure. An altimeter is a device that measures altitude, the distance of a point above sea level.

Students conduct a series of experiments to see how water depth affects pressure. They then develop a model to illustrate how pressure increases in deeper water. Join our community of educators and receive the latest information on National Geographic's resources for you and your students.

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Go Paperless with Digital. Materials Heat-resistant glass jar Rubber band that fits around the mouth of the glass jar Balloon Wooden skewer Scissors Tape Paper Pen Three bowls Tap water hot and cold Ice cubes Paper towels Preparation Cut off and discard the opening of the balloon, then stretch the remaining balloon piece around the opening of the glass jar, wrapping it tightly.

Secure the balloon to the jar with the rubber band. Tape the end of the wooden skewer flat onto the top of the balloon with the pointy tip pointing away from the jar. Fill the first bowl with room temperature water, the second bowl with hot tap water be careful with hot water, and have an adult help if necessary and the third bowl with ice water.

Place your barometer close to a wall with the skewer parallel to the wall. Tape a piece of paper behind the barometer on the wall. Draw a line on the paper that lines up with the tip of the skewer. Mark the position where the barometer is placed. You will have to place it on the same spot later during the activity. Procedure Take the barometer and place the glass jar in the bowl with the hot water.

The water should not reach beyond the rubber band. What do you observe about the barometer? Do you notice any changes? If yes, what kind of changes? After one minute take the barometer out of the water, quickly dry it off, and place it at the same spot close to the wall where you have attached the paper. Make another line on the paper so that it lines up with the pointy tip of the skewer.

Where does the tip point now? How did the barometer change? Place the barometer into the bowl with room temperature water. Again observe what happens. Keep it in the bowl for about 10 minutes. After 10 minutes how does the barometer look different from before? After 10 minutes put the barometer back at its spot by the wall and make another line on the paper where the skewer is pointing.

Atmospheric pressure is also known as barometric pressure because it is measured using a barometer. A rising barometer indicates increasing atmospheric pressure and a falling barometer indicates decreasing atmospheric pressure. Changes in air pressure are caused by differences in air temperature above the earth, and the temperature of an air mass is determined by its location.

For example, air masses above oceans are typically cooler than air masses above continents. Air temperature differences create wind and cause pressure systems to develop. The wind moves pressure systems and these systems tend to change as they pass over mountains, oceans, and other areas.

These discoveries are used to predict the weather today. Often, weather forecasters refer to high- or low-pressure areas moving toward particular regions in order to describe predicted conditions for those areas. As air rises in low-pressure systems, it cools and often condenses into clouds and precipitation, resulting in storms.

In high-pressure systems, the air sinks toward the Earth and warms upward, leading to dry and fair weather. In general, a mercury barometer can let you know if your immediate future will see clearing or stormy skies, or little change at all, based only on atmospheric pressure. The mercury in the tube will adjust itself to match the atmospheric pressure above the dish. As the pressure increases, it forces the mercury up the tube. The tube is marked with a series of measurements that track the number of atmospheres or bars.

Observer s can tell what the air pressure is by looking at where the mercury stops in the barometer. In , the French scientist Lucien Vidi invented the aneroid barometer. An aneroid barometer has a sealed metal chamber that expand s and contract s, depending on the atmospheric pressure around it. Mechanical tools measure how much the chamber expands or contracts. These measurements are align ed with atmospheres or bars.

The aneroid barometer has a circular display that indicate s the present number of atmospheres, much like a clock. One hand moves clockwise or counterclockwise to point to the current number of atmospheres. The terms stormy, rain, change, fair, and dry are often written above the numbers on the dial face to make it easier for people to interpret the weather.

Aneroid barometers slowly replaced mercury barometers because they were easier to use, cheaper to buy, and easier to transport since they had no liquid that could spill.