On Wednesday, June 20, 2018 at 5:22:22 AM UTC-6, Paul Schlyter wrote:

In article ,
says...

On Friday, June 15, 2018 at 10:43:29 AM UTC-6, Mike Collins wrote:
...............
And it wasn?t a project. It was just farmers using greenhouses
( often makeshift) to grow crops. You may not be aware of a similar
effect in the USA.

http://www.sciencemag.org/news/2018/...ts-own-weather

Thanks, Mike, that's VERY interesting, although some of the speculation
about what is causing it seems counter-intuitive. For example, they say
it might be due to photosynthesis releasing H2O, but H2O is a greenhouse
gas and should have an opposite effect.

H2O is also a gas which frequently condenses in our atmosphere and is
then transformed to liquid form as a large number of small droplets.
These droplets form clouds, which reflects incoming light from the Sun,
causing a cooling. Rain can also fall out from the couds, which causes
additional cooling.


Indeed!

So increased H2O alone does not necessarily warm the atmosphere, it might
just as well cool it. However, if the atmosphere is warmed in some other
way, e.g. by increased CO2, then it can hold more H2O before it
condenses, and then the greenhouse effects of H2O can increase the
effects of CO2 warming.

On the planet Mars, CO2 plays a similar role as H2O does on Earth, since
on Mars, CO2 can condense and evaporate. That never happens naturally on
Earth.