Humidity and its affect on play
Alexander J. Chien
Hi All -
I had been reading a bit of how playing altitude and temperature
can affect the playing conditions of table tennis dramatically. Last night,
I played ata club where I think conditions played quite a role. It was very
humid last night and I was wondering if any others out there have similar
observations in humid playing conditions :
1) I found it very hard to loop. The ball felt as if it was not
completely grabbing to my rubber sheet, or perhaps the
sponge of my sheet seemed much less elastic. Whatever the
reason (perhaps I need a new sheet, or my stroke needs work)
my loops never got enough distance on them.
2) Play seemed slower. Smashes, loops (when I could hit them) didnt
seem to have much on them last night.
Are these playing conditions representative of very humid weather?
-Alex
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/ \ Alexander Chien | Olympic Table Tennis
| | ajc...@med.umich.edu | Atlanta, USA 1996
O \___/\ 'Loop to Kill' - Mincon Panther Pro-S and Donic Vario
\\\ founder of usenet rec.sport.table-tennis
\/
James Fortune
> I had been reading a bit of how playing altitude and temperature
>can affect the playing conditions of table tennis dramatically. Last night,
>I played ata club where I think conditions played quite a role. It was very
>humid last night and I was wondering if any others out there have similar
>observations in humid playing conditions :
> 1) I found it very hard to loop. The ball felt as if it was not
> completely grabbing to my rubber sheet, or perhaps the
> sponge of my sheet seemed much less elastic. Whatever the
> reason (perhaps I need a new sheet, or my stroke needs work)
> my loops never got enough distance on them.
The moisture would explain less grabbing of the rubber. With less tangential
force on the ball it would not take less elasticity of the rubber to get
less distance than you are used to. If your others shots got their normal
distance then this is what is happening.
Other comments:
I remember in a senior fluids class that by using spherical coordinates and
using the separation of variables technique on the differential equation
the professor proved that rotating spheres curve more rapidly through air
as the air density increases. So if you played at a high altitude the lower
density would tend to straighten out the trajectory slightly. I haven't
looked into how humidity affects air density.
> 2) Play seemed slower. Smashes, loops (when I could hit them) didnt
> seem to have much on them last night.
>Are these playing conditions representative of very humid weather?
The high humidity and lack of air motion would definitely make you heat
up quickly. This could explain some of the slower play :-). The smashes
being slower hints at the elasticity since those shots are relatively
flat. If the smashes had a lot of spin then you're back to the friction.
Perhaps some dropped ball tests will help determine what's happening here.
Usually when it's warm and humid I have enough trouble keeping the sweat
off the raquet face but I'll pay more attention to differences the next time
I play in humid conditions. Sorry I couldn't be of more help.
Before: After: (angle changes also)
\ |
\ | \ |
\ | \ |
\ | \ |
____\| ____\|
A related rhetorical question (2 parts):
Is it possible to hit a ball with NO normal component (i.e., all spin
but with the tangential force used to impart the spin supplying the force
needed to carry the ball over the net)? How do you execute this shot?
JAF
--
James Fortune - Internet: Thousands of people mostly unaware
Oakland University - of the sight and sound of each other, linked
jafo...@vela.acs.oakland.edu - together by the bits of our souls that can
Disclaimer: Not O.U. opinions - fit through computer keyboards.
Larry Rose
Both humidity and altitude effect the speed of the ball. Lower
altitude and higher humidity both slow down the ball, and make
the effect of spin more dramatic. Since I live in Colorado, with
altitude of 6,500 feet, and about 35-40% humidity, and often travel
to sea level and play in 90% humidity areas, I am very familiar with
the effects. If you are travelling from one extreme to another, you
must change your playing style considerably. When I play at lower
altitudes, I find that I have to be more agressive - or at the least,
more ready to return the next shot, as my loops don't go past my opponents
quite as readily. At higher altitude, increasing the spin (which makes
the loop drop faster due to the Bernoulli effect) is very important. You
can also be somewhat less agressive in your shot selection, because the
ball speed will be faster.
Acclimating yourself to different conditions can be mentally taxing, but
if you think about the process, you can change your game rather quickly.
Generally, it is easier to go to lower altitudes or higher humidity, because
you have more time to react. If you are travelling to higher altitudes, a
day of practice prior to a tournament can do wonders.
Larry Rose
Rocky Mountain Table Tennis Association
Tournament Sanctioning Director
MALOUF, PERRY
>using the separation of variables technique on the differential equation
>the professor proved that rotating spheres curve more rapidly through air
>as the air density increases. So if you played at a high altitude the lower
>density would tend to straighten out the trajectory slightly. I haven't
>looked into how humidity affects air density.
>
I sent to him directly through E-mail.
Message-ID: <7MAY1993...@estd.nrl.navy.mil>
References: <1sb49j$e...@terminator.rs.itd.umich.edu> <1sc6qi$h...@vela.acs.oakland.edu>
Organization: ESTD - Naval Research Laboratory, Washington DC
News-Software: VAX/VMS VNEWS 1.41
Concerning the subject of how humidity affects air density; humidity
lowers air density. This can be noticed in hang gliding and regular
glider soaring. For a given air temperature and aircraft, lift
is noticeably stronger on days with lower humidity. A more extreme
example can be found when flying powered aircraft. I've noticed that,
while flying in a commercial jet, when one wing of the jet passes
through a cloud while the other wing is clear then the jet tends
to bank into the cloud until the pilot initiates correction. This
is because the wing in the cloud loses some lift compared with the
other wing. The same physics principles apply to fluid flow around
a rotating ping pong ball.
By the way, the effect of a ball
curving while it is travelling and spinning in air is called
the Magnus effect. Although the principle of Bernoulli is
fundamental to the Magnus effect, the latter is used to
describe the phenomenon. Magnus was a scientist commissioned
to study why cannonballs veered off course when fired at a
target.
Cheers!
Perry Malouf
ma...@levels.unisa.edu.au
I have also noticed these effects.
In addition, a smash is likely to bounce off the air just before it is about
to land on the table, and rise rather than fall - most disparaging.
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