B
Bill Sornson
Guest
nafuk wrote:
> On 7 Jan, 22:56, "Jack May" <[email protected]> wrote:
>> "Stephen Harding" <[email protected]> wrote in message
>>
>> news:Zhxgj.9242$Xo1.4668@trnddc06...
>>
>>> Jack May wrote:
>>>> "Stephen Harding" <[email protected]> wrote in message
>>> I think I read that during the Carboniferous period that
>>> the earth was as hot as it has ever been.
>>
>>> ISTR that one of the reasons was due to large amounts of
>>> water vapor in the air (volcanoes? geothermal activity?).
>>> Can't remember what the source of it was. Maybe just
>>> evaporation from oceans.
>>
>>> At any rate, the air can be very heavily saturated with
>>> water without it raining, or without rain clearing up
>>> the humidity. Check out many of the tropical locations
>>> of the world where heavy rains don't lessen humidity.
>>
>> From:
>>
>> http://www.wxdude.com/humidity.html
>>
>> Air can only hold 100% relative humidity. For rain the 100% relative
>> humidity is at the altitude where the rain is coming from, not the
>> ground where the humidity gage is normally. It takes some time for
>> the 100% humidity "mist" to form into drops which fall as rain.
>> There are cases where there can be super cooled water being more
>> than 100%, but that is rare.
>>
>> So for all practical purposes vapor is not going to do much to
>> increase global warming because it will precipitate out as rain when
>> it reaches 100% humidity at some place in the atmosphere. Since we
>> get rain now, the air is often saturated at some place with the
>> maximum moisture it can hold.
>
> There are three gases emitted by aircraft which contribute to global
> warming: H2O, CO2 and NOx The most obvious is the water vapour which
> forms condensation trails - clouds of frozen ice crystals. Since the
> air in the upper troposphere (the level at which most commerical
> planes fly) is naturally very dry, water vapour emitted by aircraft
> can make a big difference. Sometimes the contrails cover the whole
> sky. Have you ever wondered, why the sky is so much clearer in remoter
> locations?
>
> Although these contrails reflect a little sunlight away from earth,
> they reflect back to earth much more invisible infra-red (heat)
> radiation which would otherwise escape to space - and therefore they
> have an overall warming effect. This is hard to measure accurately,
> because the contrails eventually spread out and become
> indistinguishable from natural cirrus clouds.
>
> Not all of the water vapour forms contrails, but water is itself a
> "greenhouse gas" which also traps this outgoing infra-red radiation.
> Each water molecule traps much more heat and also survives much longer
> at this height than it would do at sea-level.
>
> Jet-fuel - kerosene - is a mixture of substances produced by
> distilling crude oil, which can be represented by C13H28. The chemical
> equation for burning it is as follows:
> 2C13H28 + 40O2 =>26CO2 + 28H2O
>
> So you can see, that for every 14 water molecules produced, the
> aircraft must also emit 13 of CO2. This is also a greenhouse gas and
> will stay in the atmosphere warming the earth for an average of 100
> years, some of it for 1000s of years. There's no way that you can get
> the energy from such fossil fuel without producing that much CO2. It's
> not a by-product that can be "scrubbed" from the exhaust.
So...Al Gore should quit riding around in his 1970s-era Gulfstream? Don't
hold your breath! (You'll just emit a greenhouse gas, anyway!)
Bill "this **** would be really, really funny if it wasn't taken so really,
really seriously by so really, really many" S.
> On 7 Jan, 22:56, "Jack May" <[email protected]> wrote:
>> "Stephen Harding" <[email protected]> wrote in message
>>
>> news:Zhxgj.9242$Xo1.4668@trnddc06...
>>
>>> Jack May wrote:
>>>> "Stephen Harding" <[email protected]> wrote in message
>>> I think I read that during the Carboniferous period that
>>> the earth was as hot as it has ever been.
>>
>>> ISTR that one of the reasons was due to large amounts of
>>> water vapor in the air (volcanoes? geothermal activity?).
>>> Can't remember what the source of it was. Maybe just
>>> evaporation from oceans.
>>
>>> At any rate, the air can be very heavily saturated with
>>> water without it raining, or without rain clearing up
>>> the humidity. Check out many of the tropical locations
>>> of the world where heavy rains don't lessen humidity.
>>
>> From:
>>
>> http://www.wxdude.com/humidity.html
>>
>> Air can only hold 100% relative humidity. For rain the 100% relative
>> humidity is at the altitude where the rain is coming from, not the
>> ground where the humidity gage is normally. It takes some time for
>> the 100% humidity "mist" to form into drops which fall as rain.
>> There are cases where there can be super cooled water being more
>> than 100%, but that is rare.
>>
>> So for all practical purposes vapor is not going to do much to
>> increase global warming because it will precipitate out as rain when
>> it reaches 100% humidity at some place in the atmosphere. Since we
>> get rain now, the air is often saturated at some place with the
>> maximum moisture it can hold.
>
> There are three gases emitted by aircraft which contribute to global
> warming: H2O, CO2 and NOx The most obvious is the water vapour which
> forms condensation trails - clouds of frozen ice crystals. Since the
> air in the upper troposphere (the level at which most commerical
> planes fly) is naturally very dry, water vapour emitted by aircraft
> can make a big difference. Sometimes the contrails cover the whole
> sky. Have you ever wondered, why the sky is so much clearer in remoter
> locations?
>
> Although these contrails reflect a little sunlight away from earth,
> they reflect back to earth much more invisible infra-red (heat)
> radiation which would otherwise escape to space - and therefore they
> have an overall warming effect. This is hard to measure accurately,
> because the contrails eventually spread out and become
> indistinguishable from natural cirrus clouds.
>
> Not all of the water vapour forms contrails, but water is itself a
> "greenhouse gas" which also traps this outgoing infra-red radiation.
> Each water molecule traps much more heat and also survives much longer
> at this height than it would do at sea-level.
>
> Jet-fuel - kerosene - is a mixture of substances produced by
> distilling crude oil, which can be represented by C13H28. The chemical
> equation for burning it is as follows:
> 2C13H28 + 40O2 =>26CO2 + 28H2O
>
> So you can see, that for every 14 water molecules produced, the
> aircraft must also emit 13 of CO2. This is also a greenhouse gas and
> will stay in the atmosphere warming the earth for an average of 100
> years, some of it for 1000s of years. There's no way that you can get
> the energy from such fossil fuel without producing that much CO2. It's
> not a by-product that can be "scrubbed" from the exhaust.
So...Al Gore should quit riding around in his 1970s-era Gulfstream? Don't
hold your breath! (You'll just emit a greenhouse gas, anyway!)
Bill "this **** would be really, really funny if it wasn't taken so really,
really seriously by so really, really many" S.
