Air stratification experiment

Introduction

This experiment works best in a room with a very high ceiling. It also works best when there is a mixture of warm and cold air in the room. This might occur early in the day during the winter, when there is still cold air in the room but the heating system has been on long enough to warm some of the air.

Objective

To observe that warm air rises and cold air settles (air stratification).

Equipment required

You will need:

• DrDAQ data logger with two external temperature sensors
• BluTack
• Meter stick

Experiment setup

Set up the DrDAQ so that it is connected to the printer port of your computer. Connect both of the external sensors. Wrap something around the cable for Ext1 so that you can tell which one is which (although you will soon be able to tell from the graph!)

Let one of the external sensors hang down 3–5 cm above the floor. Don’t let it touch the floor, because the floor itself might be warmer or colder than the air right near the floor. Use BluTack to hold it in place against the wall, but make sure it’s not touching the wall either. It should have air all around it.

Place the DrDAQ at about 1 metre from the floor, but don’t put it right above the computer monitor. The monitor gives off heat, and this will affect the sensor readings.

Have your teacher use a bit of BluTack to stick the other external sensor about one metre above the DrDAQ.

Carrying out the experiment

Using the pull-down menus, select the external sensor that is up high to be displayed on channel “A”. Then select the “Temp” sensor for channel “B”, and the other external sensor on channel “C“. The graph should show the temperature reading for the high sensor in blue, the middle one in red, and the low one in green.