A thermometer is a weather instrument that is used to measure the temperature of the air or other substances. It can be based on various principles such as thermal expansion, electrical resistance, or infrared radiation.
A barometer is a weather instrument that is used to measure the atmospheric pressure or the force exerted by the air on a unit area. It can be based on various principles such as liquid columns, springs, or aneroids.
A rain gauge is a weather instrument that is used to measure the amount of precipitation that falls in a given area and time. It can be based on various principles such as tipping buckets, weighing gauges, or optical sensors.
An anemometer is a weather instrument that is used to measure the speed and direction of the wind. It can be based on various principles such as rotating cups, propellers, or ultrasonic waves.
A hygrometer is a weather instrument that is used to measure the humidity or the amount of water vapor in the air. It can be based on various principles such as wet and dry bulb thermometers, hair tension, or electrical capacitance.