Try this interactive applet to explore the relationships between
temperature, dew point temperature and relative humidity.
Instructions are below.
Questions to Consider:
The background picture depicts a winter scene. The blue thermometers represent the outside air temperature and dew point temperature. You control the out side temperature and dew point with your mouse. To change the temperature point to the red bar of the thermometer, hold down the left mouse button, and pull the fluid up or drag it down. You change the dew point temperature the same way using the thermometer that represents dew point. You can not change the relative humidity (the blue dial) directly. You must change the relative humidity by adjusting the temperature and/or the dew point.
To practice, set the outside temperature to 30F and the dew point temperature at 0F. Leave the dew point alone and change the temperature to observe its impact on relative humidity. Once you understand that relationship, leave the temperature alone and change the dew point to see how that affects the relative humidity. We do not allow the temperature to be less than the dew point temperature. So if you increase the dew point temperature above the temperature, it automatically adjusts itself.