Tag: geography

• Based on the given data, January has maximum temperature of $26^0$.
  
• Hence, it is the hottest month.
  
• July has the minimum temperature of $11^0$. So, it is the coldest month.

Stevenson's Screen is used to shield meteorological instruments from precipitation and direct external radiations, such as heat. The screen is louvered to allow air to circulate around the instruments. Additionally, the screen is painted white to reflect the sun’s direct rays. This facilitates meteorological instruments such as thermometers and thermographs to measure temperatures in a standardized environment.

The Stevenson's Screen forms part of all-weather stations and was designed by Thomas Stevenson.

To measure the minimum and maximum temperature in a day, Six’s thermometer is used.  It consists of a U-shaped capillary tube having bulbs at both ends. Mercury is filled in the bend of the U-tube. One of the bulbs is completely filled with alcohol and the other bulb is partly filled with alcohol. Alcohol is the thermometric liquid in case of Six’s thermometer. Change in temperature is recorded due to expansion and contraction of alcohol.

Diurnal range of temperature is the difference between the maximum and minimum temperatures of the same days. Cloud cover, urban heat, land-use change, aerosols, water vapor, and greenhouse gases are caused due to changes in the diurnal range of temperature. As the distance from the sea increases diurnal range of temperature also increases. In dry tropical climates and on high mountain plateaus where solar radiation is maximum, diurnal range of temperature increases.

Stevenson screen is used for providing shelter for meteorological instruments, particularly wet and dry bulb thermometers. It is kept 1.25 meters above the ground by legs. It is done so to avoid strong temperature gradients at ground level. Stevenson screen has sides to encourage the free passage of air. For reflecting heat radiation, it is painted white. It was invented by the British engineer and meteorologist Sir Thomas Stevenson.

A device which is used to measure atmospheric pressure is known as Barometer. There are two types of barometers:- mercury and aneroid.

Atmospheric pressure is balanced by a column of mercury in case of a mercury barometer.

Aneroid barometer also called non-liquid barometer. Because of its smaller size and convenience, it is widely used in portable instruments and in aircraft altimeters.

Degree Celsius is the standard unit to measure temperature. It was developed by Swedish astronomer Andres Celsius in 1742. In degree Celsius, zero degrees represents the freezing point of water and 100 degrees represents water’s boiling point at the standard atmosphere. The standard atmosphere is the mean barometric pressure at the mean sea level.

Isohyets are imaginery lines joining places of equal rainfall. These lines are generally drawn on a weather map.

Celsius is the scale which measures temperature. It was developed by Swedish astronomer Andres Celsius in 1742. Freezing point of the water is the temperature at which water starts converting into ice. As per the Celsius scale, zero degrees is the freezing point of the water. The boiling point is the temperature at which water starts converting into vapors. As per Celsius scale, 100 degrees is the boiling point of the water.

The mean annual rainfall is calculated for data collected for a long period of time (30 - 35) years because rainfall is highly variable from day today. It adequately characterizes the rainfall regime in an area and its surroundings. World Meteorological Organization (WMO) recommends continuous 30-year records to calculate mean annual rainfall.