This applet allows you to explore the relationship between temperature, dew point temperature and relative humidity. You have control over the outdoor values by sliding the red colored portion of the two thermometers (one for temperature and one for dew point). The Relative Humidity meter will instantly tell you the value for the outside.

The applet simulates what happens inside your house when the temperature and dew point change outside. As you change the values outside, your indoor environment is slower to change.
Inside, you can control:

• The thermostat setting
• Whether either the furnace or air conditioner is set to go on (we start with the furnace set).
• other activities (try 'em!!)

In the winter, you probably would set the furnace to go ON when the temperature inside falls below the Thermostat setting. In the summer, you may set the air conditioner to go ON when the indoor temperature rises above the Thermostat setting.

Questions to consider:

• What happens to the relative humidity when the temperature decreases?
• What happens to the relative humidity when the dew-point temperature decreases?
• Does lowering the dew-point always cause a change in the relative humidity?
• Why do many homes in cold climates have low relative humidities? (Hint: Make the outside temperature cold (-10), turn-off the furnace and open the door. Then close the door and turn on the furnace.