wrote in message
ups.com...
| It may be unscientific, but it does happen, regularly, you just have to
| like cricket to notice it.
|
| I have been interested in this for many years, wondering if vapour
| pressure was the culprit, but vapour pressure can be high on a summers
| day with a high dewpoint but no low cloud and the ball doesn't swing at
| all. However, on a cool morning with low stratus the ball will move in
| the air until the stratus burns off and then not swing for the rest of
| the day.
| The Australia-Bangladesh odi at Sophia Gardens was a superb example of
| this.
|
| I have to admit that I am stumped, for an explanation.
|

As one who follows the coverage on Channel 5, I can report it happens in
baseball as well, but here it seems to mostly affect the ball after it has
left the bat - there being some ballparks where the local conditions seem to
enable the ball to be hit vast distances while others seem to result in
similar hits being caught inside the park. The stadium where Toronto Blue
Jays play has had the embarrassment of staging "weather delays" in spite of
having an overall roof (which takes 20 minutes to close), because they don't
like to close it if at all avoidable as it is claimed having the roof closed
affects how the ball flies. And some of the smaller indoor stadia with air
conditioning used to rouse suspicion that the settings were adjusted
depending on whether the home team were batting or fielding, although the
wave of new ballparks has resulted in most, if not all, of these now having
been replaced.

As for what effect humidity has, the balls the sports in question use are
capable of absorbing water and this affects the nature of the ball's
surface. I would suspect that this change affects the airflow over the
moving ball (remembering that to "swing" a cricket ball normally requires
the surfaces either side of the seam to be of different roughnesses which is
why the bowlers polish one side; or to spin the ball rapidly which is how a
baseball pitcher throws a "curve") in such a way as to make it more
sensitive to the processes which cause the ball to swing in the first place,
which from articles I have read relate to how the flow "separates" and
"rejoins" on passing round the ball.
--
- Yokel -
oo oo
OOO OOO
OO 0 OO
) ( I ) (
) ( /\ ) (

"Yokel" now posts via a spam-trap account.
Replace my alias with stevejudd to reply.