A rainband is an area of rainfall where all the clouds and precipitation are stretched out in a long line or band. Rainbands can be stratiform or convective. They are caused by differences in temperature. When seen on a weather radar, the long narrow shape is called a banded structure. Rainbands in a tropical cyclone are curved and may even spiral around the center of the cyclone. Tropical cyclone rainbands include rain showers and thunderstorms. When this includes an eyewall and the eye, they make a hurricane or tropical storm. The size of rainbands around a tropical cyclone helps to measure the cyclone's intensity.