Weather Instruments: Tools Used to Measure the Weather World

Weather instruments are devices used by atmospheric scientists to sample the state of the atmosphere, or what it's doing, at a given time.

Unlike chemists, biologists, and physicists, meteorologists don't use these instruments within a lab. Instead we place them outdoors as a suite of sensors referred to as . Below is a beginner's list of the basic weather instruments found in weather stations and what it is each measures.

01
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Anemometer

wx station winds
A small, backyard personal weather station. Terry Wilson/E+/Getty Images

Anemometers are devices used to measure winds.

While the basic concept was developed by Italian artist Leon Battista Alberti around 1450, the cup-anemometer wasn't perfected until the 1900s. Today, two kinds of anemometers are most often used:

  • the three-cup anemometer, which determines wind speed from how fast the cupwheel spins and wind direction from the cyclical changes in cupwheel speed; and
  • vane anemometers, which have propellers on one end to measure wind speed and tails on the other for determining wind direction.

02
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Barometer

A barometer is a weather instrument used to measure air pressure. Of the two main types of barometers -- mercury and aneroid -- aneroid are more widely used. Digital barometers, which use electrical transponders, are used in most official weather stations.

Italian physicist Evangelista Torricelli is credited with inventing the barometer in 1643. To learn more about how barometers work, read How Does a Barometer Measure Air Pressure?

03
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Thermometer

Petra SchrambAhmer/Getty Images

Thermometers -- one of the most widely recognized weather instruments -- are tools used to measure ambient air temperature.

The SI unit of temperature is degrees Celcius, but in the U.S., we record temperatures in degrees Fahrenheit.

04
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Hygrometer

First invented in 1755 by Swiss "renaissance man" Johann Heinrich Lambert, the hygrometer is a tool that measures air's moisture content (humidity).

Hygrometers come in all types, including:

  • hair tension hygrometers, which relate the change in length of a human or animal hair (which has an affinity to absorbing water) to a change in humidity; and
  • sling psychrometers, in which a set of two thermometers (one dry and one moistened with water) are spun in the air.

Of course, as is true of most modern weather instruments used today, the digital hygrometer is preferred. Its electronic sensors change in proportion to how moist or dry the air it is exposed to is.

05
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Rain Gauge

If you have a rain gauge at your school, home, or office you know what it measures -- liquid precipitation!

Although the first known rainfall records date back to the Ancient Greeks and 500 B.C., the first standardized rain gauge wasn't developed and used until 1441 by the Joseon Dynasty of Korea. Any way you slice it, the rain gauge is still among the oldest weather instruments in existence.

While a number of rain gauge models exist, the most widely used include standard rain gauges and tipping-bucket rain gauges (so-called because it sits on a seesaw-like container that tips over and empties out whenever a certain amount of precipitation falls into it).

06
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Weather Balloon

Arctic wx balloon launch
A balloon is released at the South Pole in order to measure ozone levels. NOAA

A weather balloon or sounding is a sort of mobile weather station in that it carries instruments into the upper air in able to record observations of weather variables (like atmospheric pressure, temperature, humidity, and winds), then sends back this data during its suborbital flight. It is comprised of a 6 foot in diameter helium- or hydrogen-filled latex balloon, a payload package (radiosonde) that encases the instruments, and a parachute that floats the radiosonde back to the ground so that it can be found, fixed, and reused.

Weather balloons are launched at over 500 locations worldwide twice per day -- usually at 00 Z and 12 Z.

07
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Weather Satellites

goes poes diagram
Satellites can be polar orbiting (cover the Earth in a north-south pattern) or hover over one spot (east-west). The COMET Program (UCAR)

Weather satellites are used to view and gather data about Earth's weather and climate. What kinds of things do meteorological satellites see? Clouds, wildfires, snow cover, and ocean temperatures just to name a few.

Just like rooftop or mountaintop views offer a wider view of your surroundings, a weather satellite's position several hundred to thousands of miles above Earth's surface allows for weather in a neighboring part of the U.S., or that hasn't even entered the West or East Coast borders yet, to be observed. This extended view also helps meteorologists spot weather systems and patterns hours to days before being detected by surface observing instruments, like weather radar.

To learn more about how satellites work, read Weather Satellites: Forecasting Earth's Weather from Space.

08
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Weather Radar

Doppler radar tower
NOAA

Weather radar is an essential weather instrument used to locate precipitation, calculate its motion, and estimate it's type (rain, snow, hail) and intensity (light or heavy).

First used during World War II as a defense mechanism, radar was identified as a potential scientific tool when military personnel happened to notice "noise" from precipitation on their radar displays. Today, radar is an essential tool for forecasting precipitation associated with thunderstorms, hurricanes, and winter storms.

In 2013, the National Weather Service began upgrading its Doppler radars with dual polarization technology. These "dual-pol" radars send and receive horizontal and vertical pulses (conventional radar only sends out horizontal) which gives forecasters a much clearer, two-dimensional picture of what's out there -- be it rain, hail, smoke, or flying objects.

More: Do you know what thunderstorms look like on radar?

09
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Your Eyes

blue sky
Absodels/Getty Images

There's one very important weather observing instrument we haven't mentioned yet...the human senses!

Weather instruments are necessary to , but they can never replace human expertise and interpretation. (If that were the case, we wouldn't need human forecasters at all!) No matter what your weather app, indoor-outdoor weather station records, never forget to verify it against what you observe and experience in "real life" outside your window and door.

In-Situ vs. Remote Sensing

Each of the above weather instruments uses either the in-situ or remote sensing method of measuring. Translated as "in place," in-situ measurements are those taken at the point of interest (your local airport or backyard). In contrast, remote sensors collect data about the atmosphere from some distance away. Can you guess which weather instruments listed above use which method?