They use barometers to measure the atmospheric pressure. The lower the pressure the more likely there is weather coming. The higher the air pressure the more likely the skies will either become mostly sunny or totally clear off and bring sunny skies.
weather and physical
Thetools scientist use are Barometers, Anemometer's thermometers Richter Scale
Barometers, Anemometer, Thermometer
There are two types of barometers, Mercury barometers and then Aenroid barometers.
mercury barometers and aneroid barometers both measure air pressure.
Mercury and aneroid barometers.
anaeriod barometer and a mercury barometer
Many do, but not all. Most barometers that people would have in their homes are aneroid barometers, which don't contain any mercury.
If it goes down the weather gets worse. If it goes up it get sunny and nice.
Pilots use barometers to see the air pressure from the plane.
They are more portable and can be used for airplane equipment
Digital barometers, much like analog barometers, are used to forecast the weather using humidity, air pressure, and dew point. This answer needed a few more characters.