Publication No. 10361
Student Laboratory Kit
Materials Included In Kit
Cotton wick, 2 feet
Additional Materials Required
Be sure that the thermometers are securely attached to the plastic handle before swinging. Inspect the assembled sling psychrometer prior to student use. Be careful not to drop or break the thermometers. Wear protective eyewear. Follow all normal laboratory safety guidelines.
The assembled sling psychrometer may be saved for future use.
Correlation to Next Generation Science Standards (NGSS)†
Science & Engineering PracticesPlanning and carrying out investigations
Analyzing and interpreting data
Using mathematics and computational thinking
Disciplinary Core IdeasMS-ESS2.D: Weather and Climate
HS-ESS2.D: Weather and Climate
Stability and change
Bonnet, R. L.; Keen, G. D. Earth Science—49 Science Fair Projects; TAB Books, USA, 1990; pp 124–126.
In this activity, a sling psychrometer will be constructed and the relative amount of humidity in the air will be measured. The dew point will then be found using the relative humidity value.
Water vapor is the gaseous, invisible form of water in the atmosphere. It is better known as humidity. When the air in the atmosphere contains a large amount of water, the air feels very humid. The opposite is true when the air is relatively void of water vapor—the air feels very dry. When air holds the maximum amount of moisture, dew or frost will be present and small droplets will begin to form as clouds. As the clouds become saturated with water droplets, they will become too dense to hold all of the droplets and the droplets will start to fall towards the Earth’s surface in the form of rain or snow. This is known as 100% humidity.
Be sure that the thermometers are securely attached to the plastic handle before swinging. The instructor should inspect the assembled sling psychrometer prior to use. Be careful not to drop or break the thermometers. Wear protective eyewear. Follow all normal laboratory safety guidelines.
Student Worksheet PDF