Measuring Humidity

PocketLab Voyager, Weather, and Air all measure relative humidity (%RH). Learn about relative humidity and what affects it here.

Air can hold a certain amount of water vapor depending on the temperature. Warmer air can hold a greater amount of water vapor. Colder air can hold less water vapor. Relative humidity is a percentage that gives the amount of water in the air relative to the maximum amount of water the air can hold at the current temperature.

Water vapor in your breath

Quantify the water vapor in your breath by exhaling near your PocketLab. You should see a significant change in the relative humidity reading. How does this relate to “seeing” your breath in cold temperatures?

How are air temperature and relative humidity related?

To investigate, use your PocketLab to record the air temperature and relative humidity outside for one hour. Try again every six hours for 24 hours. You can also use your PocketLab’s onboard memory to continuously record data for all 24 hours (see instruction manual for details on using the onboard memory).

Before you begin, predict what time of day you think the air will be the hottest and coldest. Predict what time of day you think the air will be the most humid and least humid.

After collecting the data, determine whether your predictions were correct. When was the hottest and coldest part of the day? When was the most humid and least humid part of the day? How did those results relate to sunrise and sunset? How is relative humidity related to air temperature? Can you see that relationship in the results of your experiment?