The maximum/minimum thermometer is a U-shaped tube with two separate temperature readings, one for the maximum temperature and one for the minimum temperature.
Calibration
Prepare a mixture of liquid water and crushed ice and allow it to sit for 10 to 15 minutes so that it will reach its lowest temperature. The thermometer can then be placed in the bath. If the thermometer does not read between 0.0 and .5&Mac176; C students should use another thermometer. The thermometer should then be placed in an instrument shelter and after 24 hours students can compare it to the maximum/minimum thermometer. If the temperature differ, the maximum/minimum thermometer should be calibrated to the temperature of the calibration thermometer.
Measuring Min/Max Current Air Temperature
Students should mount the maximum/minimum thermometer in the instrument shelter about 1.5 meters above the ground. The thermometer should be attached to blocks on the rear wall of the shelter so that no part of it touches the walls. The shelter protects the thermometer from radiation from the sun, sky, ground and surrounding objects, but allows air to flow through. Students should first assign a team of students to read the thermometer daily within one hour of noon. While reading the thermometer, students must be sure to stand as far away as possible so as not to allow breath, touch or body heat to impact the reading. Students should read both sides of the maximum/minimum thermometer and take the maximum and minimum readings from the base of the indicators. After the maximum, minimum and current temperatures are read, students should reset the indicators using a small magnet.
![Protocols [Image: Blue-Eyed Grass]](images/protocols_h.jpg)
