Thermometers
Thermometers are used to measure the temperature. In meteorology, the most commonly used thermometer is the maximum and minimum thermometer.
Maximum Thermometer
The maximum thermometer contains mercury with a high boiling point and it measures the maximum temperature of the day. The mercury in the thermometer expands and pushes the index up the tube when the day temperature increases. However, when the temperature drops, the mercury contracts, the index remains in position. The maximum temperature is thus recorded and the reading is taken at the end of the index closer to the mercury. The instrument is reset by using a magnet to draw the index back to the mercury.
Minimum Thermometer
The minimum thermometer contains alcohol with a low freezing point and it records the minimum temperature of the day. The alcohol contracts and menicus of the alcohol pushes the index down when the temperature drops. When the temperature increases, the alcohol in the tube expands, flows past the index but does not move it.The minimum temperature is obtained by reading the scale at the end of the index which is near the minicus. The instrument is reset using a magnet to draw the index up to the menicus.
Other Instruments
Other Topics
Back to Introduction