Humidity affect on biking speed - Page 2 - Cycling Mob: Road Cycling, Mountain Biking and More

07-13-2004, 07:06 AM

In article <40f3f18a$0$21383$[Only registered and activated users can see links. ]-net.com>,
[Only registered and activated users can see links. ] says...
> On a day with a high humidity (everything else being equal) would it take
> more energy to bike a certain distance than on a day with low humidity since
> a person has more resistance from the moisture.
>
> Thanks

Water vapor is *less* dense than air (molecular weight 18, vs Nitrogen
at 28 and Oxygen at 32), so the air resistance would likely be less on a
humid day. This causes big problems for propeller-powered airplanes in
the tropics if they aren't equipped for it.

--
Remove the ns_ from if replying by e-mail (but keep posts in the
newsgroups if possible).

07-13-2004, 07:44 AM

On Tue, 13 Jul 2004 10:02:01 -0500, Scott <[Only registered and activated users can see links. ]>
wrote:

> mary wrote:
>> On a day with a high humidity (everything else being equal) would it
>> take
>> more energy to bike a certain distance than on a day with low humidity
>> since
>> a person has more resistance from the moisture.
>>
>
> Water vapor is less dense than dry air. A more humid air mass
> is less dense than a dry air mass. Not only that, but since
> your hair is all matted down from sweat, you present less
> surface area!
>
> So you should be rocketing along on those humid days!
>
> Scott
>

Unless it's hot and humid, then your cooling mechanism, sweating, doesn't
work as well. If you get hot, you could overheat.

--
Bob in CT
Remove ".x" to reply

07-13-2004, 07:44 AM

On Tue, 13 Jul 2004 10:02:01 -0500, Scott <[Only registered and activated users can see links. ]>
wrote:

> mary wrote:
>> On a day with a high humidity (everything else being equal) would it
>> take
>> more energy to bike a certain distance than on a day with low humidity
>> since
>> a person has more resistance from the moisture.
>>
>
> Water vapor is less dense than dry air. A more humid air mass
> is less dense than a dry air mass. Not only that, but since
> your hair is all matted down from sweat, you present less
> surface area!
>
> So you should be rocketing along on those humid days!
>
> Scott
>

Unless it's hot and humid, then your cooling mechanism, sweating, doesn't
work as well. If you get hot, you could overheat.

--
Bob in CT
Remove ".x" to reply

07-13-2004, 07:44 AM

On Tue, 13 Jul 2004 10:02:01 -0500, Scott <[Only registered and activated users can see links. ]>
wrote:

> mary wrote:
>> On a day with a high humidity (everything else being equal) would it
>> take
>> more energy to bike a certain distance than on a day with low humidity
>> since
>> a person has more resistance from the moisture.
>>
>
> Water vapor is less dense than dry air. A more humid air mass
> is less dense than a dry air mass. Not only that, but since
> your hair is all matted down from sweat, you present less
> surface area!
>
> So you should be rocketing along on those humid days!
>
> Scott
>

Unless it's hot and humid, then your cooling mechanism, sweating, doesn't
work as well. If you get hot, you could overheat.

--
Bob in CT
Remove ".x" to reply

07-13-2004, 07:44 AM

On Tue, 13 Jul 2004 10:02:01 -0500, Scott <[Only registered and activated users can see links. ]>
wrote:

> mary wrote:
>> On a day with a high humidity (everything else being equal) would it
>> take
>> more energy to bike a certain distance than on a day with low humidity
>> since
>> a person has more resistance from the moisture.
>>
>
> Water vapor is less dense than dry air. A more humid air mass
> is less dense than a dry air mass. Not only that, but since
> your hair is all matted down from sweat, you present less
> surface area!
>
> So you should be rocketing along on those humid days!
>
> Scott
>

Unless it's hot and humid, then your cooling mechanism, sweating, doesn't
work as well. If you get hot, you could overheat.

--
Bob in CT
Remove ".x" to reply

07-13-2004, 07:44 AM

On Tue, 13 Jul 2004 10:02:01 -0500, Scott <[Only registered and activated users can see links. ]>
wrote:

> mary wrote:
>> On a day with a high humidity (everything else being equal) would it
>> take
>> more energy to bike a certain distance than on a day with low humidity
>> since
>> a person has more resistance from the moisture.
>>
>
> Water vapor is less dense than dry air. A more humid air mass
> is less dense than a dry air mass. Not only that, but since
> your hair is all matted down from sweat, you present less
> surface area!
>
> So you should be rocketing along on those humid days!
>
> Scott
>

Unless it's hot and humid, then your cooling mechanism, sweating, doesn't
work as well. If you get hot, you could overheat.

--
Bob in CT
Remove ".x" to reply

07-14-2004, 12:24 AM

Also, hot air is less dense. Convert temperature to Celcius (-32 * 5/9)
add 273 to convert to Kelvin. Take 273 and divide by the Kelvin
tempature to get this ratio. EG 30 Celcius (86 Ferenheit) has a ratio
of 273/373 dry air density (0% humidity). Also, warmer air can hold
more water vapor as tempature rised. A dew point of 65 degree Farenheit
means the air, if cooled to 65 F, would be at 100%. Warm the air to 90
with that days sun and the humidity is 60% with the same amount of
moisture in it. Take it to 212 F 100 C and 100% humidty means 100%
water vapor, 0% nitrogen, 0% oxygen. There are water vapor tables that
can tell you at what tempatures 100% humidity means as far as percent
water and percentage air.

David Kerber wrote:
>
> In article <40f3f18a$0$21383$[Only registered and activated users can see links. ]-net.com>,
> [Only registered and activated users can see links. ] says...
> > On a day with a high humidity (everything else being equal) would it take
> > more energy to bike a certain distance than on a day with low humidity since
> > a person has more resistance from the moisture.
> >
> > Thanks
>
> Water vapor is *less* dense than air (molecular weight 18, vs Nitrogen
> at 28 and Oxygen at 32), so the air resistance would likely be less on a
> humid day. This causes big problems for propeller-powered airplanes in
> the tropics if they aren't equipped for it.
>
> --
> Remove the ns_ from if replying by e-mail (but keep posts in the
> newsgroups if possible).

07-14-2004, 12:24 AM

Also, hot air is less dense. Convert temperature to Celcius (-32 * 5/9)
add 273 to convert to Kelvin. Take 273 and divide by the Kelvin
tempature to get this ratio. EG 30 Celcius (86 Ferenheit) has a ratio
of 273/373 dry air density (0% humidity). Also, warmer air can hold
more water vapor as tempature rised. A dew point of 65 degree Farenheit
means the air, if cooled to 65 F, would be at 100%. Warm the air to 90
with that days sun and the humidity is 60% with the same amount of
moisture in it. Take it to 212 F 100 C and 100% humidty means 100%
water vapor, 0% nitrogen, 0% oxygen. There are water vapor tables that
can tell you at what tempatures 100% humidity means as far as percent
water and percentage air.

David Kerber wrote:
>
> In article <40f3f18a$0$21383$[Only registered and activated users can see links. ]-net.com>,
> [Only registered and activated users can see links. ] says...
> > On a day with a high humidity (everything else being equal) would it take
> > more energy to bike a certain distance than on a day with low humidity since
> > a person has more resistance from the moisture.
> >
> > Thanks
>
> Water vapor is *less* dense than air (molecular weight 18, vs Nitrogen
> at 28 and Oxygen at 32), so the air resistance would likely be less on a
> humid day. This causes big problems for propeller-powered airplanes in
> the tropics if they aren't equipped for it.
>
> --
> Remove the ns_ from if replying by e-mail (but keep posts in the
> newsgroups if possible).

07-14-2004, 12:24 AM

Also, hot air is less dense. Convert temperature to Celcius (-32 * 5/9)
add 273 to convert to Kelvin. Take 273 and divide by the Kelvin
tempature to get this ratio. EG 30 Celcius (86 Ferenheit) has a ratio
of 273/373 dry air density (0% humidity). Also, warmer air can hold
more water vapor as tempature rised. A dew point of 65 degree Farenheit
means the air, if cooled to 65 F, would be at 100%. Warm the air to 90
with that days sun and the humidity is 60% with the same amount of
moisture in it. Take it to 212 F 100 C and 100% humidty means 100%
water vapor, 0% nitrogen, 0% oxygen. There are water vapor tables that
can tell you at what tempatures 100% humidity means as far as percent
water and percentage air.

David Kerber wrote:
>
> In article <40f3f18a$0$21383$[Only registered and activated users can see links. ]-net.com>,
> [Only registered and activated users can see links. ] says...
> > On a day with a high humidity (everything else being equal) would it take
> > more energy to bike a certain distance than on a day with low humidity since
> > a person has more resistance from the moisture.
> >
> > Thanks
>
> Water vapor is *less* dense than air (molecular weight 18, vs Nitrogen
> at 28 and Oxygen at 32), so the air resistance would likely be less on a
> humid day. This causes big problems for propeller-powered airplanes in
> the tropics if they aren't equipped for it.
>
> --
> Remove the ns_ from if replying by e-mail (but keep posts in the
> newsgroups if possible).

07-14-2004, 12:24 AM

Also, hot air is less dense. Convert temperature to Celcius (-32 * 5/9)
add 273 to convert to Kelvin. Take 273 and divide by the Kelvin
tempature to get this ratio. EG 30 Celcius (86 Ferenheit) has a ratio
of 273/373 dry air density (0% humidity). Also, warmer air can hold
more water vapor as tempature rised. A dew point of 65 degree Farenheit
means the air, if cooled to 65 F, would be at 100%. Warm the air to 90
with that days sun and the humidity is 60% with the same amount of
moisture in it. Take it to 212 F 100 C and 100% humidty means 100%
water vapor, 0% nitrogen, 0% oxygen. There are water vapor tables that
can tell you at what tempatures 100% humidity means as far as percent
water and percentage air.

David Kerber wrote:
>
> In article <40f3f18a$0$21383$[Only registered and activated users can see links. ]-net.com>,
> [Only registered and activated users can see links. ] says...
> > On a day with a high humidity (everything else being equal) would it take
> > more energy to bike a certain distance than on a day with low humidity since
> > a person has more resistance from the moisture.
> >
> > Thanks
>
> Water vapor is *less* dense than air (molecular weight 18, vs Nitrogen
> at 28 and Oxygen at 32), so the air resistance would likely be less on a
> humid day. This causes big problems for propeller-powered airplanes in
> the tropics if they aren't equipped for it.
>
> --
> Remove the ns_ from if replying by e-mail (but keep posts in the
> newsgroups if possible).