An extratropical cyclone turns anticlockwise in the Northern Hemisphere. The shape is circular or oval. The usual size in diameter is about 1000 km. These cyclones are usually connected with fronts. A front is a system of changes in weather. It is caused by a very cold air mass meeting a very hot air mass. In the cyclone, there is a system of warm front and cold front. The center of a cyclone is cloudier. There is also a very high chance of precipitation. The wind is strong and changes its direction, as the warm front passes. The weather is stable and fog is usual. As the cold front passes, there is a change of wind, the temperature decreases and rain is also common.