1.   Moisture is always a problem on planes, because they sit in high humidity on the ground, and then fly to cooler altitudes where the vapor condenses.

2.   The hot water vapor condenses on the cooler cone, leaving any impurities in the wick.

3.   The vapor condenses as it rises, releasing heat, which generates thunderstorms that cool the lower atmosphere while they heat the upper atmosphere.

4.   Water vapor in the air reaches saturation at dew point, and the vapor condenses in contact with surface areas, depositing droplets of water.

5.   You can insulate the pipes to stop this, but the vapor will condense on other cool surfaces.