| A dry bulb thermometer is the oldest means of accurately measuring temperature. It consists of a thin glass tube attached to a glass bulb and mounted against a numbered scale. A liquid (mercury or alcohol) is sealed inside the glass. As the air around a thermometer gets hotter or colder, the liquid rises or falls inside the glass. To tell what the temperature is, simply compare the level of the thermometer's mercury against the numbered scale on the thermometer.
A resistance thermometer is a modern temperature sensor that uses electronics to determine the temperature by measuring the change in resistance across a material such as copper, nickel, germanium or platinum.
A wet bulb thermometer measures the lowest temperature that can be obtained by evaporating water into the air. It is called "wet-bulb" because the temperature is obtained by covering the bulb with a wet material, such as a cotton ball. In order to create the evaporation effect and get the most accurate reading, air must be moving over the wet material.
Air temperature is measured on either the Fahrenheit scale (F) or the Celsius scale (C).
Note: If your thermometer uses the Fahrenheit scale, you can easily calculate the equivalent Celsius temperature reading using the formula below.
| °C = (°F - 32) / 1.8 |
°F = (°C x 1.8) + 32 |
Alternatively, you can read the Fahrenheit number on the thermometer, then look up that reading on the conversion table.
| ° F |
° C |
° F |
° C |
| -100 |
-73.3 |
-95 |
-70.6 |
| -90 |
-67.8 |
-85 |
-65.0 |
| -75 |
-59.4 |
-70 |
-56.7 |
| -65 |
-53.9 |
-60 |
-51.1 |
| -55 |
-48.3 |
-50 |
-45.6 |
| -45 |
-42.8 |
-40 |
-40.0 |
| -35 |
-37.2 |
-30 |
-34.4 |
| -25 |
-31.7 |
-20 |
-28.9 |
| -15 |
-26.1 |
-10 |
-23.3 |
| -5 |
-20.6 |
0 |
-17.8 |
| 5 |
-15.0 |
10 |
-12.2 |
| 15 |
-9.4 |
20 |
-6.7 |
| 25 |
-3.9 |
30 |
-1.1 |
| 32 |
0.0 |
35 |
1.7 |
| 40 |
4.4 |
45 |
7.2 |
| 50 |
10.0 |
55 |
12.8 |
| 60 |
15.6 |
65 |
18.3 |
| 70 |
21.1 |
75 |
23.9 |
| 80 |
26.7 |
85 |
29.4 |
| 90 |
32.2 |
95 |
35.0 |
| 100 |
37.8 |
105 |
40.6 |
| 110 |
43.3 |
115 |
46.1 |
| 120 |
48.9 |
125 |
51.7 |
|
