Well, maybe she's just a little unclear on the concept. The dew point is what the dew point is. It's a dependent variable. The independent variables are temperature and relative humidity. If the temperature reaches the dew point condensation will form on whatever there is to condense on. If the dew point is 11 then the tempearture has to reach 11 for dew (frost) to form. Now it may have gotten down to 11 up in the clouds or the relative humidty may have been higher up in the clouds (more likely) giving us a higher dew point up there. If you look at the chart you'll notice that dew point matches tempearture at 100% relative humidity.