Hello everyone,

I have what is probably a rather simple question here - but I'm struggling to solve it myself. I have a number of measurements of Integrated Water Vapour, in units of kg/m^2 and I need to provide this as an input to a model as Precipitable Water Content in cm.

Is there an easy way to convert between these? As far as I am aware, the definition of PWC is the height of the water if all of the water in the air column was precipitated out, so I guess this question is basically "What is the height in cm of X kg/m^2 of water?" - is that possible to answer with a simple conversion formulae?

Any help would be much appreciated,

Best regards,

Robin

wrote in message
news:25950344.2484.1336483371719.JavaMail.geo-discussion-forums@ynja13...
Hello everyone,

I have what is probably a rather simple question here - but I'm struggling
to solve it myself. I have a number of measurements of Integrated Water
Vapour, in units of kg/m^2 and I need to provide this as an input to a model
as Precipitable Water Content in cm.

Is there an easy way to convert between these? As far as I am aware, the
definition of PWC is the height of the water if all of the water in the air
column was precipitated out, so I guess this question is basically "What is
the height in cm of X kg/m^2 of water?" - is that possible to answer with a
simple conversion formulae?

Any help would be much appreciated,

Best regards,

Robin

================

1 kg/m^2 of water will have a height of 0.1cm.
Total column precipitable water in the UK at sea level will normally range
from 10 to 40mm, occasionally higher or lower.

Will
--

wrote:
Hello everyone,

I have what is probably a rather simple question here - but I'm struggling to solve it myself. I have a number of measurements of Integrated Water Vapour, in units of kg/m^2 and I need to provide this as an input to a model as Precipitable Water Content in cm.

Is there an easy way to convert between these? As far as I am aware, the definition of PWC is the height of the water if all of the water in the air column was precipitated out, so I guess this question is basically "What is the height in cm of X kg/m^2 of water?" - is that possible to answer with a simple conversion formulae?

Any help would be much appreciated,

Best regards,

Robin
--------------------------
I may be wrong but my quick calculation gives me the height as = X/10 cm
Derived from 1Kg water at STP = 1 litre = 1000 cubic cm. One square
metre is 10,000 square cm. Therefore for every kg of water over a square
metre would be 1mm (0.1cm) deep.
Dave

wrote in message
news:25950344.2484.1336483371719.JavaMail.geo-discussion-forums@ynja13...
Hello everyone,

I have what is probably a rather simple question here - but I'm struggling
to solve it myself. I have a number of measurements of Integrated Water
Vapour, in units of kg/m^2 and I need to provide this as an input to a model
as Precipitable Water Content in cm.

Is there an easy way to convert between these? As far as I am aware, the
definition of PWC is the height of the water if all of the water in the air
column was precipitated out, so I guess this question is basically "What is
the height in cm of X kg/m^2 of water?" - is that possible to answer with a
simple conversion formulae?

Any help would be much appreciated,

Best regards,

Robin

mw = r * (p1-p2) / g,
where mw is the precipitatable water, r is the mean value of water vapour
(over the layer confined by pressures p1 and p2), and g is acc due to
gravity.
If r is in grammes per kg, and g in m per sec per sec, then mw will be in
units of 0.1 mm.

--
Bernard Burton

Wokingham Berkshire.

Weather data and satellite images at:
http://www.woksat.info/wwp.html

"Bernard Burton" wrote in message
...
wrote in message
news:25950344.2484.1336483371719.JavaMail.geo-discussion-forums@ynja13...
Hello everyone,

I have what is probably a rather simple question here - but I'm struggling
to solve it myself. I have a number of measurements of Integrated Water
Vapour, in units of kg/m^2 and I need to provide this as an input to a
model as Precipitable Water Content in cm.

Is there an easy way to convert between these? As far as I am aware, the
definition of PWC is the height of the water if all of the water in the
air column was precipitated out, so I guess this question is basically
"What is the height in cm of X kg/m^2 of water?" - is that possible to
answer with a simple conversion formulae?

Any help would be much appreciated,

Best regards,

Robin

mw = r * (p1-p2) / g,
where mw is the precipitatable water, r is the mean value of water vapour
(over the layer confined by pressures p1 and p2), and g is acc due to
gravity.
If r is in grammes per kg, and g in m per sec per sec, then mw will be in
units of 0.1 mm.


Bernard, are you sure?
Whole mm surely?

Will
--

Yes Will, that is the fact.

Example, for a saturated column at Theta-w 10C, and taking the mean r per
100 mbar from 1000 up to 400 mbar, the values of r are 7, 5.7, 4, 2.6, 1.4
and 0.6 g/kg. That gives a total r of 21.3 * 100/9.8, or appx 213 units of
0.1 mm, or 21.3 mm.
(7 * 100) + (5.7 * 100)....etc / 9.8

--
Bernard Burton

Wokingham Berkshire.

Weather data and satellite images at:
http://www.woksat.info/wwp.html

"Dartmoor Will" wrote in message
...

"Bernard Burton" wrote in message
...
wrote in message
news:25950344.2484.1336483371719.JavaMail.geo-discussion-forums@ynja13...
Hello everyone,

I have what is probably a rather simple question here - but I'm
struggling to solve it myself. I have a number of measurements of
Integrated Water Vapour, in units of kg/m^2 and I need to provide this as
an input to a model as Precipitable Water Content in cm.

Is there an easy way to convert between these? As far as I am aware, the
definition of PWC is the height of the water if all of the water in the
air column was precipitated out, so I guess this question is basically
"What is the height in cm of X kg/m^2 of water?" - is that possible to
answer with a simple conversion formulae?

Any help would be much appreciated,

Best regards,

Robin

mw = r * (p1-p2) / g,
where mw is the precipitatable water, r is the mean value of water vapour
(over the layer confined by pressures p1 and p2), and g is acc due to
gravity.
If r is in grammes per kg, and g in m per sec per sec, then mw will be in
units of 0.1 mm.


Bernard, are you sure?
Whole mm surely?

Will
--

Yes Will, I am sure.

Example, for a saturated column at Theta-w 10C, and taking the mean r per
100 mbar from 1000 up to 400 mbar, the values of r are 7, 5.7, 4, 2.6, 1.4
and 0.6 g/kg. That gives a total r of 21.3 * 100/9.8, or appx 213 units of
0.1 mm, or 21.3 mm.
(7 * 100) + (5.7 * 100)....etc / 9.8

--
Bernard Burton

Wokingham Berkshire.

Weather data and satellite images at:
http://www.woksat.info/wwp.html

"Bernard Burton" wrote in message
...
Yes Will, that is the fact.

Example, for a saturated column at Theta-w 10C, and taking the mean r per
100 mbar from 1000 up to 400 mbar, the values of r are 7, 5.7, 4, 2.6, 1.4
and 0.6 g/kg. That gives a total r of 21.3 * 100/9.8, or appx 213 units of
0.1 mm, or 21.3 mm.
(7 * 100) + (5.7 * 100)....etc / 9.8

--
Bernard Burton

Wokingham Berkshire.

Weather data and satellite images at:
http://www.woksat.info/wwp.html

"Dartmoor Will" wrote in message
...

"Bernard Burton" wrote in message
...
wrote in message
news:25950344.2484.1336483371719.JavaMail.geo-discussion-forums@ynja13...
Hello everyone,

I have what is probably a rather simple question here - but I'm
struggling to solve it myself. I have a number of measurements of
Integrated Water Vapour, in units of kg/m^2 and I need to provide this
as an input to a model as Precipitable Water Content in cm.

Is there an easy way to convert between these? As far as I am aware, the
definition of PWC is the height of the water if all of the water in the
air column was precipitated out, so I guess this question is basically
"What is the height in cm of X kg/m^2 of water?" - is that possible to
answer with a simple conversion formulae?

Any help would be much appreciated,

Best regards,

Robin

mw = r * (p1-p2) / g,
where mw is the precipitatable water, r is the mean value of water
vapour (over the layer confined by pressures p1 and p2), and g is acc
due to gravity.
If r is in grammes per kg, and g in m per sec per sec, then mw will be
in units of 0.1 mm.


Bernard, are you sure?
Whole mm surely?

Will
--

Yes Will, I am sure.

Example, for a saturated column at Theta-w 10C, and taking the mean r per
100 mbar from 1000 up to 400 mbar, the values of r are 7, 5.7, 4, 2.6, 1.4
and 0.6 g/kg. That gives a total r of 21.3 * 100/9.8, or appx 213 units of
0.1 mm, or 21.3 mm.
(7 * 100) + (5.7 * 100)....etc / 9.8


Ah yes, my mistake.
Thanks Bernard.

Will
--

On May 8, 2:43*pm, "Dartmoor Will" wrote:
wrote in message

news:25950344.2484.1336483371719.JavaMail.geo-discussion-forums@ynja13...
Hello everyone,

I have what is probably a rather simple question here - but I'm struggling
to solve it myself. I have a number of measurements of Integrated Water
Vapour, in units of kg/m^2 and I need to provide this as an input to a model
as Precipitable Water Content in cm.

Is there an easy way to convert between these? As far as I am aware, the
definition of PWC is the height of the water if all of the water in the air
column was precipitated out, so I guess this question is basically "What is
the height in cm of X kg/m^2 of water?" - is that possible to answer with a
simple conversion formulae?

Any help would be much appreciated,

Best regards,

Robin

================

1 kg/m^2 of water will have a height of 0.1cm.
Total column precipitable water in the UK at sea level will normally range
from 10 to 40mm, occasionally higher or lower.

Will
--

Just in case you're interested, on Mars the global average is around
10 microns of precipitable water, though in the summer when the north
polar cap sublimates it can get up to a whopping 80 microns. :-)

Liam