Nice thing about riding your motorcycle is that you don't use a lot of energy to scoot down the road like on a bicycle, so as long as you're moving down here in La. it's not too bad; but when you are sitting at stoplights, it gets hot FAST: no air movement. As the water evaporates, it gives up energy; and, as the air passes over your skin (breeze), the process accelerates. It's the same basic principle as compressed gas (like freon in a closed a/c system) cooling as the pressure drops, and heating up as the pressure is increased (high side and low side of the system with a restrictor valve to slow the flow coming out of the compressor that's moving the gas). Or, if you've ever opened up a CO - 2 cartridge and let all the gas out freely, the cartridge is verrry c-c-cooold.... Stanley
________________________________ From: oldschoolgwin <[email protected]> To: Nighthawk Motorcycle Lovers! <[email protected]> Sent: Friday, September 18, 2009 10:45:33 AM Subject: [Nighthawk Lovers] Re: Who can do the math??? Exactly. I look at it like this, it requires heat to evaporate H2O (sweat), so the heat either comers from the very local air (air film around your body) cooling the air film itself, or may also come from your body (conduction) which is removing heat from you) - probably both mechanisms apply. So it's a another mechanism of heat transfer. On Sep 18, 8:02 am, stanley/ Randolph <[email protected]> wrote: > Humidity is an indication of the saturation of water vapor in the air. The > greater the humidity the less it will absorb the sweat from your skin. I can > tell you that, in Arizona, it was easy to pedal my bicycle at speed (about > 18mph), reach my destination, and ride around the block a few times to cool > off, even with temperature being around 100. Why? Because the humidity was > around 30%,max. > When we moved, I tried that here in La. and - NOT!!! I couldn''t even cool > off in an air conditioned building, the temp being around 74 instead of 90. > Why? Because the humidity is usually around 90%. Even in the building the > humidity was still around 78% at the least, because they were only chilling > the air, not removing the moisture. > That's why "swamp coolers" work in Ariz. as a form of central air, and not > here. Only problem is, if you are away from home and a sandstorm passes by, > your house is going to be full of dust when you get home. > NOW: by the same token, in the winter, that cold air is much much colder when > there is no humidity to prevent air from sucking up the moisture from your > skin and making it that much colder. > That is what wind chill factor is all about. Just like heat index. The more > humid, the greater the heat index, because the sweat is just going to sit > there and soak your clothes, not evaporate and cool you off. > Ahora - does that clear up the confusion some? > Stanley > > ________________________________ > From: Javier Garcia <[email protected]> > To: [email protected] > Sent: Friday, September 18, 2009 8:51:12 AM > Subject: [Nighthawk Lovers] Re: Who can do the math??? > > Great explanation! However I'm a litlle bit confused with Stanley's > experience. I thought that having the same temperature, the humidity will > make sensations worse: in hot weather you feel hotter, in cold weather you > feel colder. This is actually my experience, at least at rest (cero velocity). > > Javier. > > > > On Fri, Sep 18, 2009 at 2:46 AM, oldschoolgwin <[email protected]> > wrote: > >Well, if we really want to know, it's called convective heat transfer > >coefficient. We don't feel temperature, we feel heat leaving and > >entering our body. So at higher velocities the convective coefficient > >increases (h=W/m^2*K)substantially, hence heat is leaving our body at > >faster rate - then we say its cold! We should really say heat is > >leaving me very quickly (humor!). > > >In the summer in the middle of a hot day, the inside temperature may > >be 78F (air temp) and it feels hot, but in the winter when it's 78F in > >the same house it feels cold. Hmmm - why is this? Well it's because > >there are multiple mechanisms effectiving the overall (net) heat > >transfer from your body. In the summer the wall temperature is hotter > >than winter - so guess what, now your body is recieveing radiation > >(heat) at a greater rate than in the winter. So while the air is > >conducting (theoretically) heat away from your body at the same rate > >for both summer and winter (function of temperature and air velocity) > >the radiation is greater in summer so the net heat loss rate is lower > >in the summer (it's hot in hear). Consider cloudy day and sunny day > >at the same air temp (same thing radiation is the difference in > >comfort). > > >So it get's a bit complex when you take into acount the heat capacity > >of the air (function of moisture content) and air velocity (convective > >rate) - but this is the basic concept. I.E. the same reason the NH > >oil coolers are much more effective (probably at least 20X) at hwy > >speeds than when sitting at a stop sign. But then again at hwy speeds > >the engine is also generating much more waste heat it has to transfer > >to the air. > > >Hope this helps. > > >On Sep 17, 1:35 pm, stanley/ Randolph <[email protected]> wrote: > >> Yuh really don't know whut wind chill is 'til yuh've ridden in winter at > >> night in Arizona desert. Cold with humiddy is better'n cold with none. I > >> can take 30 with 95%. I can't take 50 with 30%!! > >> > >> Stanley > > >> ________________________________ > >> From: Joseph Letourneau <[email protected]> > > >> To: [email protected] > >> Sent: Thursday, September 17, 2009 2:21:08 PM > >> Subject: [Nighthawk Lovers] Re: Who can do the math??? > > >> I ride all through the winter. The only time I dont ride is if there is > >> snow and ice still on the road. The real reason I do this is cuz the gas > >> prices are so flippin' high. By the time I get to work it takes a few > >> cups of coffee and about 15 min's before my teeth stop chattering. > >> Joey > > >> --- On Thu, 9/17/09, Dennis Hammerl <[email protected]> wrote: > > >> > From: Dennis Hammerl <[email protected]> > > >> > Subject: [Nighthawk Lovers] Re: Who can do the math??? > >> > To: [email protected] > >> > Date: Thursday, September 17, 2009, 3:11 PM > >> > If I > >> > dress right, I can take about 40, no less thank you. I did > >> > ride straight thru two years. But I was a whole lot younger > >> > then. > > >> > --- On Thu, 9/17/09, Creative Residential Designs > > >> > <[email protected]> wrote: > > >> > From: Creative Residential Designs > >> > <[email protected]> > > >> > Subject: [Nighthawk Lovers] Re: Who can do the math??? > >> > To: [email protected] > >> > Date: Thursday, September 17, 2009, 8:39 AM > > >> > The temperature would be a balmy -10 which I don't do > >> > on my bike, thank you > >> > very much! ;) > > >> > ----- Original Message ----- > > >> > From: "NytWing" <[email protected]> > >> > To: "Nighthawk > >> > Motorcycle Lovers!" <[email protected]> > >> > Sent: Thursday, September 17, 2009 4:46 AM > >> > Subject: [Nighthawk Lovers] Who can do the math??? > > >> > > If the outside temperature was 44 degrees this morning > >> > when I left the > >> > > house, what did it feel like with the wind chill at 65 > >> > miles per > >> > > hour??? For those of you in the south who > >> > don't know what wind chill > >> > > is, when it's cold outside, the harder with wind > >> > blows, the colder it > >> > > feels on the body. Those of us up north know > >> > what I'm talking about... > > >> > > > >> - Hide quoted text - > > >> - Show quoted text -- Hide quoted text - > > - Show quoted text - --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Nighthawk Motorcycle Lovers!" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/nighthawk_lovers?hl=en -~----------~----~----~----~------~----~------~--~---
