Have new thermopane windows installed. These windows are supposed to be argon gas filled. The other day during early morning 3 of the glass windows fogged up on the outside from the early morning dew. The inside of the glass was fine, only the outside was affected. I have a small pond in the rear yard. What caused the exterior of the glass to have fog on it. The affected windows do not have exterior screens on them if that makes any difference. The window manufacturer said nothing was wrong with the windows and that the exterior fogging was because of the pond in the back yard about 50 feet away. I was thinking that the windows did not have argon gas as they were supposed to have. What is causing this condition as it does not happen all the time. Thanks...