Discs don't feel right? Beware of how seasonal changes can change how discs feel and fly. Sometimes this is subtle, sometimes not.

Plastic that is soft and supple at 80 degrees will start to stiffen up at 60 and become almost rigid at 40 degrees. This varies from plastic to plastic. Some will be quite rigid at 50 degrees.

If you leave your discs in your ungaraged car overnight and it get's down to freezing, your discs may be 'frozen' or at least still quite rigid when you take them out to play the next day.

What is going to happens when disc's get cold are several.

* Discs may not snap out of your fingers like they do when warm. This isn't to say your 'snap' will disappear. Rather, instead of the disc bending at release to help the release, your fingers may do a bit more work and the release point may be slightly different (or off). This can cause a subtle or large change in body/throw mechanics. It can also make your fingers hurt.

* The bead (rounded edge) at the rim of the disc will become more important at colder temperatures. Discs with larger, rounder beads may feel better and provide more control than those with sharp edges.

* Low pressure areas usually mean wind, rain and cold. The curious thing about low pressure areas is the air is actually 'thinner' than the air during warm or hot days. For example an altimeter that is set to 500 feet on an average day, may show altitudes of 100 feet on hot summer days and over 1000 feet on cold blustery days. The change in air density will change disc flight characteristics just as if you drove up or down from the hills.

* A disc that might turn a lot (one way or the other) in 'thick' air might not turn so much in thin air. Same for lift. A disc with lots of lift in hot days, may have less lift.

* If a particular shot at your favorite course requires a high degree of specificity in disc flight patterns, you might find it elusive to achieve because the air is different, not because your disc has changed.

* Plastic rebound is much slower. In other words, if you bash your disc into a tree, it will take longer for it to recover it's shape. Sometimes, it will not recover because the heat of the impact might be sufficient to reshape the plastic. Cold plastic is more sensitive to this than warm plastic.

* Discs with rubber compositions (putters) are not as effected by temperature as plastic.

Always, Fred C

Colder air is denser, so there is both more drag and more lift. Hotter air is thinner and reduces lift, so some airports do not allow landing or takeoff if the temperature exceeds a certain amount. Heat a sealed can enough and it will explode. A variation of 50 degrees Fahrenheit in temperature changes air density by 10%.

I don't know why storms are low pressure. I've been told that humid air is thinner because each water molecules weighs less than a nitrogen. Of course, there's no arguing with measurements.

Not that I care about any of this come hucktime.

Storms are low pressure because low pressure makes a storm. The low pressure came first, and caused the storm. Storms have high RELATIVE humidity because of the low pressure, because air with low pressure can't hold as much moisture. The humidity doesn't CAUSE low pressure. Take a mass of air of a certain temperature and absolute humidity. If you add pressure, you get sunny skies, if you take pressure away, the air can't hold all the moisture and dumps it in the form of clouds and rain and storms. Add pressure to a storm, it vanishes!

Pressure always comes first, and pressure is determined by the upper atmosphere pressing down on the lower. The upper 600 miles of atmosphere determines the pressure in the lower 1 or 2 miles where people live. Pressure determines the weather, the weather doesn't determine the pressure.

The only exception I can think of is the hurricain/typhoon, where low altitude events determine the pressure.

* Colder air is denser, so there is both more drag and more lift. *

This only applies when the air pressure is held equal. In uncompartmentalized nature (outside), when it's cold, it's frequently associated with a low pressure weather pattern. The effect of the lower pressure is greater than that of the colder air.

It does seem intuitively backwards, but that's the way altimeters and barometers read air density, compensated for temperature or not.

Cold weather is almost always associated with a HIGH pressure weather pattern. In the USA, cold air masses come down in waves from Canada, with high pressure. Every 3 or 4 days another cold, high pressure mass comes down from Canada to displace the low pressure tropical air from the Gulf.

What is this, the freakin weather channel?

Fred's (mis)understanding of air pressure and density needs some correction.

"* Colder air is denser, so there is both more drag and more lift. *

This only applies when the air pressure is held equal. In uncompartmentalized nature (outside), when it's cold, it's frequently associated with a low pressure weather pattern. The effect of the lower pressure is greater than that of the colder air."

The effect of temperature variation on air density is greater than the effect of air pressure variation on density, in the real world. The air is denser on a cold, winter day under a low-pressure system than on a hot, summer day under a high-pressure system.

At a fixed altitude, the widest possible variation in barometric pressure has an effect on air density which is about the same as a temperature variation of only about 10 degrees Fahrenheit. A difference of 50 degrees, for instance between a 40-degree winter day and a 90-degree summer day, will cause a much greater change in air density than will any normal variation in barometric pressure.

Also, cold air is commonly associated with high-pressure weather systems in the real world

"It does seem intuitively backwards, but that's the way altimeters and barometers read air density, compensated for temperature or not."

No, altimeters and barometers measure pressure, not density. And they are not compensated for temperature. They measure pressure directly, temperature is not part of this measurement.

Colder air is more dense than warmer air, and, in general, temperature's effect on density is greater than pressure's effect. Denser air will provide both more lift and more drag for your discs. Sky King is correct.

D = P / (T * R)
D = air density
P = air pressure (hPa or millibars)
T = air temperature (Kelvin)
R = 287 (gas constant)

The effect of humidity on air density is much, much smaller than the effects of pressure and temperature. Humid air is slightly less dense than dry air, but the difference usually insignificant in this context.

Correction to my (and Fred's) statements about altimeters. You can correct some altimeters for temerature, and the reading you get is called 'density altitude', or air density expressed as an altitude. When making this measurement, the correction for barometric pressure (the weatherman's barometric pressure number, also called the "altimeter setting") is not used. The standard setting of 29.92 inHg or about 1014 hPa is used.

Factors affecting air density, in decreasing order of significance:

Elevation (altitude)

Air temperature

Barometric pressure

Air humidity

The change in density of the plastic of the disc with change in temperature more than compensates for the changes in density of the air with temperature. Denser discs cut through the air better, nullifying the effects of the denser air.

* Cold weather is almost always associated with a HIGH pressure weather pattern. *

Depends upon your definition of cold weather and your geographic location. Really cold clear weather is typically related to high pressure. It's sort of a once or twice a year deal in the PNW. Probably happens more often elsewhere.

However, what most around here consider cold weather is associated with wind, clouds and precipitation. It's probably better termed "cool" weather rather than cold weather by some standards.

I've worn a altimeter watch for about ten years and studied it's effects for as long. On the wrist, you get a reasonable temperature compensated reading. For a barometric adjustment, one needs to get information from a fixed temperature adjusted barometric site.

As you note, the greatest factor in air density is altitude. On most cold stormy days, my altimeter watch reports altitudes about 500 feet higher than 'normal'. (For example today, it reports about 250 feet higher than it should -- we've had cold winds, rain and clouds zipping by). On sunny summer days (and super cold clear winter days, which are a moderate rarity in the PNW) it reports the altitude up to 400 feet lower than normal -- Thick air which will exaggerate some disc behavior...

For the most part the effects of variation in barometric pressure on disc flight are modest. However, they are greater than one might think. Some play and performance is undoubtable changed by these subtle changes.

"I've worn a altimeter watch for about ten years and studied it's effects for as long. On the wrist, you get a reasonable
temperature compensated reading. For a barometric adjustment, one needs to get information from a fixed temperature adjusted
barometric site."

One more time. To measure air pressure, you just measure air pressure. No temperature compensation is needed, none is warranted. To measure altitude via air pressure, you need to correct for local barometric pressure, which you get from the nearest weather station (which is usually an airport). Once again, temperature is irrelevant.

To measure air pressure, or to use pressure to measure altitude, you do not need to correct for or even know the air temperature. If you are correcting for temperature, then you are doing something wrong. If your altimeter is off by 500 feet on a cold, windy, stormy day, that is because of the barometric pressure. Temperature has nothing to do with it.

"For a barometric adjustment, one needs to get information from a fixed temperature adjusted
barometric site."

Delete "temperature adjustment" and this is correct. Altimeters and barometers measure air pressure. They do not measure air density. The barometric pressure reported by a weather station is NOT corrected for temperature. It is independent of temperature. Air pressure and air density are two different things. Weather stations do not report density of the air.

You do NOT get a "reasonable temperature compensated reading" from an altimeter. There is no such reading.

* To measure altitude via air pressure, you need to correct for local barometric pressure, which you get from the nearest weather station (which is usually an airport). *

You're missing the point, which isn't to measure the altitude above sea level of a course but the relative air density at that course on that day, relative to the air density of an average day.

When an altimeter shows 1000 feet when the altitude is really 500 feet, what it's really saying for the DGer is that your discs will fly as if the 500 foot above sea level course is really 1000 feet above sea level. This assumes you've set the altimeter to the proper altitude on an "average" day. Around here, that means run down to the ocean and set to zero.

If you want to accurately measure altitude with an altimeter, you set the altimeter while you are at to a known landmark (such as sea level). For a few hours it will be accurate to within 10 or 20 feet, depending upon the altimeter. Mine's a 20 foot model that is reasonably accurate. It changes if you run up 20 feet of hill or stairs.

You're missing the point. Barometric pressure has little effect on a disc's flight. Air density has an effect.

Your altimeter measures pressure, not density. If your reading shows a lower altitude than your "average day" setting, that means that the air pressure has changed. It does not indicate a difference in air density, which could be greater, less, or the same. And the pressure reading is not related to temperature, and no temperature compensation is used except by those who do not understand the instrument and what it measures.

Altimeters and barometers measure pressure. Aerodynamic perfomance is affected by density. Pressure and density are two distinctly different things. You can calibrate an altimeter by using a known elevation (your sea-level example) or by using a reading from a local weather station (the way pilots do it). Either way should get you a valid measurement of pressure and/or altitude. You will not get a density measurement.

I love it when two people are in a heated argument when both of them are right but arguing about different things.

"Two plus two equals four."

"No, George Washington was the first president."

"You're missing the point, 2 2 4!"

I guess the way to find the true measurement of the viscocity of the air for our purposes is to use a barometer (not an altimeter) to find the pressure, and use the formula:

Density in Disc Golf Units = Pressure / 287 K

where K is the degrees Kelvin. Here's how:

1. Convert the temperature from fahrenheit to celcius and add 273 (?) to get kelvin

2. Multiply this by 287

3. Take the pressure in inches of mercury and divide this by the result from #2 above.

4. This will give you density in DGU or Disc Golf Units.

I think the DGU's should be reported at the beginning of every tournament. Average DGU's should be published for each course in the course directory. Hell, CNN should report the DGU's daily, along with the wind chill factor and THI!

Of course, corrections should be made for locations with air polluted with dense hydrocarbons, and also for foggy days since the disc will attract water or ice.

Notice how the above does not take altitude into account, because it's not necessary. That's automatically figured in by using a barometer which will give a much lower reading at high altitude. Therefore, a course in Tibet will always have a much lower DGU figure than the Qumran course on the Dead Sea.

Wow, these guys throw Frisbees, and they are smart, too! I am impressed. Considering the PDGA demographics, many of us have college degrees, but how many of us get to impress other golfers with it?

Easily Impressed

Umm, they would only impress me if they sunk 50' putts on a regular basis. Other than that, weather changes are something we all have to deal with. Puff your chests out on another topic gentlemen.

It's impossible to sink a 50 foot putt without knowing the PGU of the hole.

Dont' you mean DGU? If so, I disagree. I have seen one or two pros make 50 foot putts without compensating for DGU. I agree that it's next to impossible for the rest of us though.

Morgan is now "official"! Morgan is the newest PDGA member #17334. It would appear that this web site is effective at recruiting new members to our community. I'm surprised that Morgan stuck with it after all the crap he took about his "chicken wing".

I'm going back to ultimate and lids. Sorry. These golf discs are all right but they aren't as much fun to throw. My 73 for 18 holes at the NY State Championships in Warwick would have been a 60 if I had used my trusty old CPI Saucer Tosser ultimate lid. Golf discs are too tippy and don't fly straight. I want a disc with enough lift that it stays straight when you throw it.

Besides, I can't get anybody around here to stop playing ultimate long enough to even try disc golf. They look at my XL and say, "That's cool" and then go on playing football. No interest.

What can I say? New York is ultimate country. As Yogi Berra would have said: "If nobody wants to play disc golf, how are you gonna stop them?"

Morgan-
move to rochester, and you wont feel like such
an oddball. i promise you. on one side of ellison park, there's an ultimate league, and on the other, a beauty of a disc golf course. i figure you can just run back and forth, and have the best of both worlds...
jamie adams
#16327

ps. also, you have to give yourself way more time w/ the sport. i've been averaging 100 holes/wk for an entire year, and i'm just now starting to notice an improvement in my game in tournament play. if i or anyone (pretty much) based whether or not to continue playing disc golf on our first tournament, i would have been finished a long, long time ago. it does help to have a support system of players and courses around, though.
good luck!

"My 73 for 18 holes ..would have been..." Yeah, right. Playing woulda/shoulda/coulda golf is pointless. I woulda shot a -36 if I aced every hole! Golf discs don't fly straight if you don't throw em right dude, just like ultimate discs. Ultimate is a team sport. Golf is a solitary pursuit, even among a crowd. You don't need anyone to play with, you are playing the course. And it's a bit of sour grapes from me. I have the lung capacity of an asthmatic humming bird, so all that ultimate running would kill me!

yeah, golf discs are too flippy and dont fly straight b/c you havent been throwing them as long as you have been throwing lids. w/ practice, practice, practice, you'll be tossing discs straighter and farther than lids. give yourself time...

Morgan, feel free to use those Ultrastars, or The Tool to play golf, they're all on the PDGA approved list (I just wouldn't recomend putting with them).

Don't tell my you guys play Ulti with non-approved discs.

NARF? There's a P&TB freak on the DG courses? That's just too Zorting Faboo.

Thanks for the encouragement. Maybe within the next year or two I'll be too old for ultimate. One hour poops me out these days, 25 years ago it would just warm me up. Maybe I'll learn disc golf.

Okay here's what I did. I contacted the UPA (Ultimate Players Assoc.) and asked them for a list of all their members with zip codes in my area. I plan to send them each a detailed letter about Disc Golf, and some info published by the PDGA to let them know about the sport.

I did the same thing with the PDGA and Brian H. graciously sent me a list of all the members in eastern NY and Vermont. Believe it or not, I'm the only person on the list in my area, not one single person on that list lives within 100 miles of me. And the list was pretty short of people within 200 miles of me!!

I've got a tough row to hoe.

Dang Morgan, most people would love to be the best disc golfer within a hundred mile radius;-)

...but most people over 15 don't like to play with themselves. :->

Okay Morgan, I'm moving into your area soon. Melrose NY is near Troy. Got a job there. I will help you start a golf scene there, big time. And I can't wait to see your chicken wing.

It's a 'rookie' mistake to leave your discs in the car in the wintertime and play with them when they are cold - they do fly much differently. It's better to leave them inside overnight and allow them to slowly acclimate to the ambient temperature during your first round. They also break more easily when ice cold! (Although that happened a lot more the era of DX plastic, today's champion plastic is a lot tougher)

Wow! Talk about dragging up an old thread! :)

I am bored with the current threads. :D

I have a question about disc flight in different seasons. I only learned how to really throw a driver this winter and wanted to know how my plastic will fly this summer. I know discs fly further, but how they get there is really important for the courses I play (lotta trees up here :D) In other words, will discs act more stable or less stable? Is the stuff I'm turning over now going to get really flippy? Is my overstable stuff going to turn into z-xtremes? I'm used to playing in the snow, with cold, frozen plastic -- sometimes a little ice under the rim is just the thing to keep a disc stable in a howling headwind on a -20 windchill day. /msgboard/images/graemlins/smirk.gif

Ultimately, the differences will be subtle and best learned by experience.
Hot air rises, so you'll get more lift generally in a warm clime than a cold one.
If you're competing, everyone in that climate will experience the same differences anyway, thereby levelling the playing field. :cool:

Hey Jeff, I'm kind of wondering why you think that leaving your discs indoors overnight is going to make them stay warm the whole next day. It takes a disc 30 seconds to become cold again when you take it outdoors.

I hope your chemistry skills are better than your physics.

Oh yeah, I forgot about your fuzzy pink disc warmers

Hey assjack, I didn't say they would stay warm the ENTIRE day. I'm talking about discs left out in the car overnight being very brittle. You would think you would know about discs shattering on trees since you hit trees on nearly every drive.

Unless you play in Minnesota in the middle of January, discs kept indoors overnight take a significant amount of time for the core temperature to decrease and come to equilibrium, which might save them from breakage.

For an optometrist, you sure can't see very well what is written. What a dope.

Hey assjack, I didn't say they would stay warm the ENTIRE day. I'm talking about discs left out in the car overnight being very brittle. You would think you would know about discs shattering on trees since you hit trees on nearly every drive.

Unless you play in Minnesota in the middle of January, discs kept indoors overnight take a significant amount of time for the core temperature to decrease and come to equilibrium, which might save them from breakage.

For an optometrist, you sure can't see very well what is written. What a dope.



Assjack that a new one, funny :)

just throw gateway discs in the cold. They never break!

The US energy problem has just been solved by Jeff La Grassjack. We can just use the amazing heat storage properties of golf discs. They store so much heat, it takes days or months to release it all. Cold places like Maine can set up giant golf disc solar energy farms and heat up the discs all summer, and during the winter the heat they release will keep the whole state warm until late February.

Warm discs in the winter suck. Snow sticks to them.

And I play in the middle of January in Minnesota.

Don't worry Greg. Jeff is only talking about the "core temperature" of the disc. The disc has a core, didn't you know? And the core has a different temperature than the outside, says Jeff. So the outside of the disc can be cold and the snow brushes off the disc even though the central core of the disc is like 90 degrees. Right Jeff?

Whatever, douchebag. No sense in having a battle of wits with an unarmed person.

Whatever, douchebag. No sense in having a battle of wits with an unarmed person.



Morgan must be feeling the LOVE.......

Silly Silly hippie man.....

Cold discs SUCK!!!!!!!!!!!

Dude, my first ICE BOWL was at Rockburn DGC in scenic Maryland, the temp. got up to 14 degrees. I'll never forget the looks on the faces of my team mates when my DX Raven expoded on impact with that tree. Classic :eek:

the spot will be played from the largest piece. :D