2011-09-15 18:09:35Water evaporation from trees
Paul D

chillcast@googlemail...
82.18.130.183

This looks interesting. Seems like some new research (others as well as this) will need to be included in climate models:

http://www.sciencedaily.com/releases/2011/09/110914161729.htm

2011-09-15 18:11:15
Paul D

chillcast@googlemail...
82.18.130.183

BTW I searched the ERL site but couldn't find the paper.

http://iopscience.iop.org/1748-9326

2011-09-15 18:50:08
Rob Painting
Rob
paintingskeri@vodafone.co...
118.92.34.188

Paul, full paper available here.

Look forward to your post on the subject! 

2011-09-15 19:08:35
MarkR
Mark Richardson
m.t.richardson2@gmail...
192.171.166.133

I'm confused by this bit:

 

"The researchers even thought it was possible that evaporation could have a warming effect on global climate, because water vapor acts as a greenhouse gas in the atmosphere. Also, the energy taken up in evaporating water is released back into the environment when the water vapor condenses and returns to earth, mostly as rain. Globally, this cycle of evaporation and condensation moves energy around, but cannot create or destroy energy. So, evaporation cannot directly affect the global balance of energy on our planet."

 

 

It affects the temperature gradient and surface temperatures though. That's what the lapse rate feedback's all about. By moving energy up with latent heat you partly 'short circuit' the greenhouse effect. and get it to space faster. It reduces warming.

2011-09-15 19:17:50
nealjking

nealjking@gmail...
91.33.127.254

MarkR:

H2O vapor doesn't get much beyond 10 km in altitude.

CO2 gets to about 100 km.

2011-09-15 19:22:04
Rob Painting
Rob
paintingskeri@vodafone.co...
118.92.34.188

Neal, I think you're missing Mark's point. 

2011-09-15 19:24:11
nealjking

nealjking@gmail...
91.33.127.254

Are you getting it?

2011-09-15 19:41:11
Rob Painting
Rob
paintingskeri@vodafone.co...
118.92.34.188

Yup, evaporation promotes cooling at the surface and nudges heat out to space quicker. So it does have a noticeable affect on the distribution of heat. That's why the tropical rainforests, such as the Amazon, were able to survive when global temperatures were higher than today. It promoted surface cooling. Sadly though, there is going to be precious little water to evaporate off and promote cooling in the near future, because weather patterns in the future are going to differ greatly from the past. And many tropical trees just so happen to be operating just a fraction below their thermal tolerance level.

The blurb he's responding to is from Science Daily so it's not surprising it's a bit mangled.

Interesting to see the effect quantified though. I remember reading a few papers on the emergence of Angiosperms (flowering trees) and how they were thought to have a vast effect on cooling of the global climate over the last 90-60 million years, because of their superior ability to soak up and recycle water.

2011-09-16 01:17:50
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Finally something that I am familiar with :)

Yup, the canopy interception of precip is important, not only for re-evaporatin but for transpiration.  In some recent I recently did we found that our simnple model (which does not allow for interception and evaporation of precip) tended to significantly underestimate transipration (and thus evapotranspiration) folllowing notable rainfall events. We did not look how that affected canopy and ambient temperatures.  Canopy interception also reduces the amount of moisture that makes it into the soil, and that can have consequences for evaporations as well as transpiration form the canopy owing to soil moisture stress.

How best to deal with canopy interception of rainfall and its re-evaporation is challenging, but there are several numerical schemes out there that try and mimic this process and they do a pretty good job, for the most part.

Anways Paul, if I can help in any way give me a shout...but then again, for all I know this subject is in fact your area of expertise ;)

OK, whoever decides to write it up...

2011-09-16 01:44:00
Paul D

chillcast@googlemail...
82.18.130.183

I don't think it will be me!

Mutley is sniggering for a good reason.