In meteorology, usually the “eye of the storm” (hurricane, typhoon), that is, the roughly circular area of comparatively light winds found at the center of a severe tropical cyclone and surrounded by the eyewall. The winds increase gradually outward from the center but can remain very light up to the inner edge of the eyewall. No rain occurs and in intense tropical cyclones the eye is clear with blue sky overhead. Most, but not all, tropical cyclones with maximum winds in excess of 40 m s−1(78 knots) have eyes visible on satellite imagery. Eye diameters vary from 10 to more than 100 km.