Nowadays, we can see weather stations present even at farm levels. An adequately equipped local weather station allows the populace to plan operations and minimize losses properly. Now, let us look into the working of sensors used in weather station.
Working of Weather Station Sensors
The sensors used in Weather Stations are thermometers, barometers, hygrometers, anemometers, pyranometers, rain gauges, wind vanes, and windsocks. Larger cutting edge stations may also use precipitation identification sensors, disdrometers, transmissometers, ceilometers, etc.
The instruments are usually present inside a protective box, except a few which require direct contact and exposure to atmospheric elements. All of these sensors transmit the recorded data to computer or display units. Lets see the working of each sensor in detail.
A device capable of measuring the temperature is known as a thermometer. It is the most popular and basic sensor. It consists of a temperature sensing unit and a unit that can present this recorded data in the form of a numerical value.
An absolute thermodynamic scale is agreed upon internationally to avoid confusion. Liquid thermometers, dial thermometers, electronic thermometers, measuring thermometers are some of the types of thermometers.
When the thermometer's tip comes in contact with the material it is supposed to test, the heat energy is conducted throughout the device, and the reading is displayed on the scale. Using this basic principle, both internal and external temperatures can be measured.
Ergo, Weather Station Sensors come equipped with thermometers that can measure temperature both inside and outside. The sensor present outside is covered with a radiation shield for protection.
Temperature sensors present in the thermometer send the collected data to a console. These sensors are of three kinds- A thermocouple consisting of two wires made of different materials fused at one end. A thermistor (resistant) made up of a cylinder tube containing metallic oxides and PTD probes made of platinum to record even a small degree rise in temperature.
It is a device used to record the humidity of the air. There are two types :
It is made up of moisture attracting material(atmospheric moisture causes humidity) and consists of two bulbs like thermometers out of which one is covered with a wet towel to measure the temperature difference between the two bulbs once the water in the towel has evaporated. These can record both indoor and outdoor humidity as well.
It is placed near the temperature sensor in a weather station unit. It is a type of capacitor with a dielectric polymer layer and a thin metal electrode inside. The hygrometer can absorb water molecules from the air. This moisture absorbance causes a change in capacitance, which can be measured to find out humidity levels.
Wind speed and direction is measured with the help of an anemometer. For wind speeds to be comparable from one point to another, various factors are considered. The standard height is usually 10 meters high in open terrain.
In weather stations, following three kinds of anemometers are used.
It consists of the cup-like structures used to measure wind speed along with a vane to measure direction (vane always points against the course of wind).
It comes with a standard vane and propeller to measure the wind's speed and direction. The propeller faces wind direction by the action of the vane, and the data is displayed.
This uses ultrasonic waves to transmit wind data. Its appearance resembles tenna, which has places for passage of air. Wind speed influences ultrasonic wave speed, and data is transmitted.
The barometer is a special instrument by which we measure the air pressure. Change in pressure causes an array of changes in weather. If the pressure measuring device records and measures pressure at varying altitude levels, it is called an altimeter.
However, a barometer is used to measure pressure changes at a particular single altitude. The average land pressure is 940-1040hPaa, while sea level has an average pressure of 1013hPaa. As the pressure decreases, there is a high chance of stormy weather.
A mercury barometer consists of a capillary glass tube with a mercury-filled basin at the bottom. The glass tube has an open and closed sid and is submerged in a mercury reservoir. The air pressure is the driving force of the movement of mercury in the tube, causing a vacuum suction. The height of the mercury is recorded, and the calculated pressure data is sent to the console.
An aneroid barometer measures pressure without the involvement of fluid. It is made up of a small mechanically flexible box or aneroid cell ( with a complete absence of air) on beryllium and coppe along with a manually set needle sensitive to even minute pressure changes. They are safer than mercury barometers.
These are meteorological instruments that can collect and measure rainfall (and snowfall) levels. They find the utmost importance in various industries like food and agriculture, as they can help predict rainfall trends.
Standard Rain Gauges
It consist of a funnel with a collecting unit at the bottom. The collected rainwater is magnified ten times, and the data is sent for further calculations.
Autographic Rain Gauges
It have a recording chart mounted on a drum which rotates every day. They can tip themselves after collected water reaches a certain level. An electric mark is made, and collected water is tipped out of the gauge. It is connected to a data console for transmission.
These are devices used to measure the solar radiation flux density of the hemisphere of a flat surface. They can normally operate without power or minimum power requirements.
They are made up of two domes and a black absorber. One of the domed filters the radiation transmitted by the sun while the second dome improves the first's performance.
The black body absorbs this filtered radiation, and flux density is calculated. These are two types made up of thermophile or silicon cells. The recorded data is sent to a computer unit for further screening.
Wind Vanes and Socks
A wind vane is an instrument to measure the direction of the Wind. As it helps in finding the direction and origin of wind, it can be used to find the origins of storms.
Its construction is very simple. It consists of a spindle mounted on a horizontal plate, allowing a fin to move in the direction of the wind's origin.
A windsock is used to measure the direction and speed of the wind. It consists of a huge textile conical sock-like structure wrapped around a long pole that flaps around, giving information on the wind strength to a trained eye.
Both wind Vanes and Socks can be used ornamentally, but they are usually connected to the main data console in weather stations.
This is the working of some of the basic sensors used in weather station systems. All the data recorded through these sensors are transmitted to the computer unit or data console and processed by experts to forecast the weather.
About the Author
I am Tim, a weather enthusiast who loves to watch hurricanes and all other harsh weather conditions. I studied B.Sc(Meteorology) at the University of Miami. With excellent knowledge of Weather Forecasting, Meteorology, and Environmental Science, I am currently working in San Francisco as a Meteorologist. Also, I am a member of The Weather Channel and AccuWeather. In this blog, I will write a detailed review of Weather instruments that you need for survival and other activities.