Cover the roof of the aquarium evenly with zip-lock bags of ice. Make sure that the bags are well sealed so that there are no leaks. Wait a few minutes. Add more ice bags if necessary.
Check the aquarium every ten minutes. Where do you see water? Is the water moving in the aquarium. Note the water level in the bowl. How much water is in the bowl? Diagram the aquarium and the condensation patterns.
Record temperatures at each end and in the middle of the aquarium. Note the evaporation of water from the bowl, the movement of the water in the aquarium and each thermometer's temperature. Does the temperature gradient correlate with the movement of water?