This picture shows what effect of a hurricane?

The stadium effect is how the inside of a well-defined eye of a hurricane can appear to look like a bowl-shaped stadium. It is caused by air parcels rising in a spiral within the eye wall, moving outwards from the core of the storm as they rise. This motion causes the eye to become wider as the altitude above the oceans surface increases. The clouds surrounding the eye slant upward and away from the storm's center as altitude increases, forming the shape of a stadium. The clouds that make up the surrounding eye wall take on the role of stadium seating, while the lower, clearer portion near the center of the eye is the playing field.