Freezing of water in a vertical closed tube partially embedded in the ground

Freezing of water accumulated on the bottom in a vertical closed tube partially embedded in the ground is considered by means of numerical calculations. The wind temperature below the freezing temperature changes periodically with 1 day cycles. Freezing is considered with changing the wind-temperature and -velocity, the tube length and the heat conduction in the soil around the tube. Natural convection in the tube plays a key role for the freezing of the water.