The Stevenson screen holds instruments that may include thermometers (ordinary, maximum/minimum), a hygrometer, a psychrometer, a dewcell, a barometer and a thermograph. Its purpose is to provide a standardised environment in which to measure temperature, humidity, dewpoint and atmospheric pressure.

What is the function of the Stevenson screen?

A Stevenson screen (also known as an instrument shelter) is a meteorological screen to shield instruments against precipitation and direct heat radiation from outside sources, while still allowing air to circulate freely around them.

Why is the Stevenson screen painted white?

Stevenson screens are always painted white to better reflect the sun’s rays. The louvered sides allow outside air to flow around the thermometers. At some locations, the airflow is assisted by a psychrometer motor that pumps outside air across the instruments inside.

Why is Stevenson screen made of wood?

The box is made of wood to prevent absorption and conduction of heat. The four sides of the box are louvered so that the air will still be able to enter and circulate freely.

What are the characteristics of weather station?

Typical weather stations have the following instruments: Thermometer for measuring air and sea surface temperature. Barometer for measuring atmospheric pressure. Hygrometer for measuring humidity.

Why is Stevenson screen raised above the ground?

It is kept 1.25m/4.1ft (UK standard) above the ground by legs to avoid strong temperature gradients at ground level, has louvred sides to encourage the free passage of air, and is painted white to reflect heat radiation, since what is measured is the temperature of the air in the shade, not of the sunshine.

How does a Stevenson screen measure temperature?

To take temperature measurements, thermometers are placed inside instrument enclosures known as a Stevenson screen. A Stevenson screen is basically a box with louvres that allow air to circulate around the thermometer inside while protecting it from outside elements like rain and direct sunlight.

Is a rain gauge kept in a Stevenson screen?

The Weather station

A major structure in a weather station is a Stevenson screen. The other instruments in a weather station include a rain gauge, wind vane, anemometer, evaporimeter, windsock, sunshine recorder etc.

Why is a hygrometer kept in a Stevenson screen?

Photo: This traditional weather station contains a hygrometer and other weather forecasting equipment. The white louvered box, called a Stevenson screen, protects the instruments from the direct heat of the Sun but allows air to circulate inside, so giving more reliable measurements.

Why does the Stevenson screen have metal stands?

It allows for the free circulation of air around the thermometer thus creating a uniform temperature in the screen. The base of the screen is position at about 1.25 –2metres above the ground on a metal stand. Thermometers which indicate the actual temperature are known as ordinary thermometers.

Why is the Stevenson screen made out of wood and not metal?

This is basically a box with louvered sides, often made of wood, so air can flow through, painted white to reflect sunlight – characteristics intended to make the conditions inside the box as near to the outside conditions as practical while simultaneously protecting instruments from precipitation and condensation.

What defines climate?

Climate is the long-term pattern of weather in a particular area. Weather can change from hour-to-hour, day-to-day, month-to-month or even year-to-year. A region’s weather patterns, usually tracked for at least 30 years, are considered its climate.

What are the 7 weather elements?

The basic atmospheric conditions that make up the weather include precipitation, humidity, temperature, pressure, cloudiness, and wind.

What are the 12 weather instrument?

Some of the most commonly used weather instruments. (a) Thermometer: temperature, (b) Anemometer: wind speed, (c) Rain gauge: amount of rain, (d) Hygrometer: humidity, (e) Wind vane: wind direction, (f) Snow gauge: amount of snow.

How do you monitor weather conditions?

6 tools our meteorologists use to forecast the weather
Doppler radar. A National Weather Service Doppler radar tower in Springfield, Missouri. ( Satellite data. GOES-16, NOAA’s newest weather satellite, launched in late 2016. ( Radiosondes. Automated surface-observing systems. Supercomputers. AWIPS.

How do you maintain a Stevenson screen?

Just remove the thermometer set from the Stevenson Screen and run the entire unit under a stream of fresh, cool water for several minutes. This will help dissolve the salt spray and keep corrosion under control. Dry the unit off with a clean cloth and replace back in the screen.

Why Stevenson screen is kept at a height of 1.5 m above the surrounding area?

Explanation: I believe it is to have a standardised hight at which to make weather observations. The temperature at ground level is often much lower in the morning, and higher in the afternoon. There is a specific “liquid in glass” (alcohol usually) terrestrial thermometer for measuring ground temperature.

What is a screened thermometer?

Definition of thermometer screen

: a structure that shelters a thermometer from direct sunlight and other conditions that would cause the thermometer to give erroneous readings of the free air temperature.

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