Most of the water in the atmosphere evaporates from the oceans. Temperature changes produce evaporation and condensation. Humidity Humidity is the amount of water vapor in the air. This amount changes slowly. Relative humidity, which is the number you hear on the weather report, changes a lot with temperature change from sunrise to sunset and into the night.
Warm air holds more moisture than cold air.
Make sure the outside of the can is dry, then drop ice into the water. Observe the outside of the can. Stove, pan of water, a clear glass shallow baking pan, enough ice to cover the bottom of the pan. Cover the bottom of the glass baking dish with ice. When there is a lot of steam rising, hold the pan of ice above the boiling water so the steam hits the pan of ice.