barometer
A barometer is an instrument used to measure atmospheric pressure. It can measure the pressure exerted by the atmosphere by using water, air, or mercury. Pressure tendency can forecast short term changes in the weather. Numerous measurements of air pressure are used within surface weather analysis to help find surface troughs, high pressure systems, and frontal boundaries.
anemometer
This would be a barometer. When the air pressure drops, you can expect rain or other bad weather like thunderstorms. On the other hand, when the air pressure rise, you can expect better weather. You can tell by using a barometer.
An anemometer is used to measure
A Rain-Gauge: a calibrated container with a specially-designed funnel. Simple but effective! They would have to use more sophisticated devices if monitoring the weather remotely.
Usually the instrument used is called a barometer- which could be a closed end manometer or an aneroid barometer.An altimeter actually also measures atmospheric pressures - but for a different purpose.
The atmosphere has numerous measurable properties, including pressure, temperature, humidity, velocity. Each of these is measured by a different instrument. Pressure is measured by a barometer, temperature is measured by a thermometer, etc.That would be a barometer. I assume you are referring to atmospheric pressure.
The ceilometer instrument.
That would be meteorology.
A tape measure.
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it would be a ruler