A golf ball has a core, an inner cover, an outer cover, and dimples, and satisfies the following mathematical formulas.

Vw=54+0.01(2.5AB+5Cv)58.0

0.08X.sup.24.25X+34520D0.08X.sup.24.25X+345+20

A: a compression of the golf ball

B: a hardness difference between a surface and a center of the core

Cv:(HiTi+HoTo)/(Ti+To)

Cs:(HiTi+2HoTo)/(Ti+2To)

D: a total volume of the dimples

X:Sw/Vw

Hi: a hardness of the inner cover

Ho: a hardness of the outer cover

Ti: a thickness of the inner cover

To: a thickness of the outer cover

Sw: 3000+10(AB1.5Cs)

A golf ball dimple pattern based on a square dipyramid, i.e., two square pyramids connected base-to-base, is disclosed. The dimples are arranged within four substantially identical triangular sections on each of two substantially identical hemispheres of the ball.

A golf ball dimple pattern based on a square dipyramid, i.e., two square pyramids connected base-to-base, is disclosed. The dimples are arranged within four substantially identical triangular sections on each of two substantially identical hemispheres of the ball.

A golf ball has a plurality of dimples 12 and a land 14 on a surface thereof. The golf ball further has a large number of minute projections 18 formed on surfaces of the dimples 12 and the land 14. The surface of the golf ball has an arithmetic average height Sa of not less than 0.5 m and not greater than 30 m. An average value Hav of heights H of the minute projections 18 is not less than 0.5 m and not greater than 50 m. A ratio Pp of a sum of areas of all the minute projections 18 to a surface area of a phantom sphere of the golf ball is not less than 7%. An average value Dav of diameters D of the minute projections 18 is not less than 5 m and not greater than 50 m.

In a multi-piece solid golf ball having a core, an envelope layer, an intermediate layer and a cover, the envelope layer is formed into two layersan inner envelope layer and an outer envelope layer. The inner envelope layer-encased sphere, outer envelope layer-encased sphere, intermediate layer-encased sphere and ball have respective surface hardnesses that satisfy a specific relationship. The inner envelope layer or outer envelope layer is formed primarily of one or more thermoplastic elastomer selected from the group consisting of polyester elastomers, polyamide elastomers, polyurethane elastomers, olefin elastomers and styrene elastomers. This ball has an excellent flight when struck by golfers whose head speeds are not that fast and has a good, soft feel at impact, thus making it highly suitable for amateur golfers.

The present invention is directed to golf balls having improved aerodynamic performance due, at least in part, to the selection of the plan shapes of the dimples thereon. In particular, the present invention is directed to a golf ball that includes at least a portion of its dimples having a plan shape defined by a periodic cosine function mapped along a circular closed path. In addition, the present invention provides methods for designing dimples having a plan shape defined by a periodic cosine function mapped along a circular closed path.

The present invention provides a golf ball wherein each hemisphere has a dimple pattern based on a pyramid having dissimilar sides. The resulting overall dimple pattern is not based on preexisting polyhedral, and is not attainable using conventional dimple packing methods.

A golf ball has a large number of exposed portions 22 on a surface thereof. An average value Hav of heights H of these exposed portions 22 is not less than 0.5 m and not greater than 50 m. The surface of the golf ball has one or more first zones and one or more second zones. An average value Hav1 of the heights H of the exposed portions 22 on these first zones is higher than an average value Hav2 of the heights H of the exposed portions 22 on these second zones. Preferably, the average value Hav1 and the average value Hav2 satisfy the following mathematical formula.
3(Hav1Hav2)50

A golf ball having a cover with a plurality of dimples on the surface thereof is provided with a coat of mutually differing properties on dimple areas of the surface and on land areas between the dimples. The dimple areas are formed with a coat having a low coefficient of friction, do not affect the spin performance when the ball is struck and are not prone to staining. The land areas are formed with a coat having a high coefficient of friction, enabling a lower spin rate to be achieved and thus increasing the distance traveled by the ball, particularly when struck with a middle iron, and also help impart a high spin rate and a good controllability on approach shots.

A golf ball has a plurality of dimples 12 and a land 14 on a surface thereof. The golf ball further has a large number of minute projections 18 formed on surfaces of the dimples 12 and the land 14. An average depth Fav of the dimples 12 and an average height Hav of the minute projections satisfy the following mathematical formula (1).
Hav/Fav0.050(1)
A ratio M (%) of a sum of areas of all the dimples 12 relative to a surface area of a phantom sphere of the golf ball and an average value Pav (m) of pitches P each between a minute projection 18 and another minute projection 18 adjacent to this minute projection 18 satisfy the following mathematical formula (2).
M/Pav>0.3(2)