Thermometers are instruments that are used for the measurement of temperature. At weather observatories, there are four types of thermometers used, which are placed inside a Stevenson screen. These thermometers are a Dry bulb thermometer, Wet bulb thermometer, Maximum Thermometer, and Minimum Thermometer. Maximum and Minimum thermometers have to be reset after taking their readings at their standard timings. For the dry bulb thermometer and wet bulb thermometer, there are no set timings. These types of thermometers are used to measure the outdoor air temperature. These thermometers are also used for measuring the indoor air temperature. The thermometers are calibrated by using the standard thermometer.
Why Maximum and Minimum Thermometers are Being Reset?
If you have ever worked with temperature monitoring equipment, you know that the maximum and minimum thermometers are reset at 0300Z UTC. The reason for this is that the maximum and minimum thermometers are calibrated based on the ambient temperature. After the reset, the new values of maximum and minimum temperatures can be recorded on the next day at 0300Z UTC by these thermometers. If thermometers are not reset then the thermometer might show the wrong values of maximum and minimum temperatures. Let’s say there was a minimum temperature of 5 degrees celsius on a day. If a thermometer is not being reset properly it will show the same reading 5 Celsius for temperatures above 5 degrees.
How To Reset Maximum and Minimum Thermometer?
Maximum and Minimum thermometers are reset by a simple procedure:
Hold the thermometer in your hand. Jerk your arms gently so that the thermometers show nearest to current temperature readings. Place back thermometers in a Stevenson screen and close the lid of the screen. Note down the readings of both maximum and minimum thermometers.
Why Mercury thermometers are Still Popular?
Mercury thermometers are still the most popular type of thermometer, despite their many problems. The mercury thermometer has been around for more than 300 years and is still used in many homes and businesses across the globe. Digital thermometers are also available nowadays which provide automatic data. Digital thermometers not only provide current temperatures but also the previous values of temperatures. Some digital thermometers have the capacity to transmit temperature data through the internet. Although digital thermometers are compact and easy to use mercury thermometers are still popular due to their accuracy and reliability.
Infrared thermometers are also available in the market. These thermometer uses the property of infrared radiation to measure the temperature of a body. Infrared radiation is invisible to the human eye. The body emits infrared rays which reflect on the surface of the thermometer. A thermometer measures the difference between the emitted and reflected rays. A thermometer measures the temperature of a body by measuring the difference in the radiation.
Can We Rely on Temperatures available on the Internet:
Temperatures available on the internet can be a useful tool for estimating temperatures in specific locations, but they should not be the only source of information used to make temperature decisions. Temperatures available on the internet are usually provided by automated weather stations and different numerical weather models. The accuracy of these data depends upon the weather station’s placement, the frequency and reliability of maintenance, and the accuracy of the equipment itself. The data provided by numerical models are not hundred percent accurate because of the complexity of the atmosphere. Therefore, it is important to use all available sources of data to make an informed decision about temperatures. Therefore temperature data recorded by using a thermometer at standard conditions is the most accurate and reliable data. World Meteorological Organisation has predefined standards for all weather related data which are followed worldwide.