What is a Stevenson screen used for?
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.
What are the main features of a Stevenson screen?
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.
Why is it called a Stevenson screen?
The screen was invented by the Scottish civil engineer Thomas Stevenson (1818–87, the father of Robert Louis Stevenson, the author). It came into use in the late 1860s.
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.
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.
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 Stevenson screen is facing north?
Stevenson screens are always painted white to better reflect the sun’s rays. Stevenson screens are always installed so that the door opens facing north, to keep the sun from shining directly on the thermometers and affecting the readings.
Why is a 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.
Why is Stevenson screen erected on stilts?
Why Stevenson screen is 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.
What Colour is the Stevenson screen?
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.
Does a Stevenson screen measure rainfall?
A Stevenson screen or instrument shelter is a shelter or an enclosure to meteorological instruments against precipitation and direct heat radiation from outside sources, while still allowing air to circulate freely around them. It is white in color to reflect direct solar radiation.
What are the features of the Stevenson screen?
The Stevenson Screen or thermometer screen is a standard shelter (from rain, snow and high winds, but also leaves and animals) for meteorological instruments, particularly wet and dry bulb thermometers used to record humidity and air temperature.
The roof of the Stevenson Screen is made of double-layered wood such that the air space provides insulation and prevents the box from overheating. The Stevenson Screen is painted white so that it can reflect light and reduce the absorption of heat which can cause temperature readings to be abnormally high.
What are the characteristics of Stevenson screen?
It is 1.2 meters above the ground to avoid ground weather conditions from affecting the readings yielded by the housed instruments.
What instruments are kept in a Stevenson screen?
Thermometers are kept in the Stevenson Screen. Thermometers like maximum/minimum, a hygrometer, a psychrometer, a dewcell, a barometer and a thermograph are kept in the Setevenson Screen. Maximum and Minimum themometer hygrometer psychrometer Dewcell Barometer Thermograph Thank You For Your Attention.
