Bertha strengthened as it slowly moved west over the warm waters of the Atlantic Ocean. Bertha grew from a tropical storm to a major hurricane (Category 3 storm).
Published Jul 17, 2008
TRMM reveals that although Bill did not yet have an eye or eyewall, it did have a well-developed cyclonic circulation as evidenced by the curvature in the rain bands that spiral in towards the center.
Published Aug 17, 2009
