David Randall: The Role of Clouds and Water Vapor in Climate Change

[@citizenschallengeYT]

At 45:30 - Can someone explain why cloud cover seems to increase when atmospheric H2O concentration drops?

[@jottes3776]

Its explained at the end of the lecture, in the questions part.

[@nicholasveridiculity91]

Now just compare ultraviolet and cosmic ray flux with cloud data and we'll really start to see an amplifying effect. It is important to note that, over the Arctic Ocean (being higher in latitude), colder temperatures (which increase the likelihood of low clouds formation) are more present in Winter, combining with higher clouds in Summer to serve as a greenhouse for irradiance: where low clouds hold heat underneath more effectively as they thicken during Winter and solar minimums (increasing with cosmic rays during solar minimums).

[@kjaanishji2595]

Wonderful lecture! Thanks prof. David

[@markyoung8613]

Cloud cover increases because less water vapour means cloud formation happens at the point of precipitation. Ie warm moist air moves into an area of dry air and therefore is attracted to other water molecules quickly (molecular structure, oxygen always has 2 free ports (electrons), if anything comes near the oxygen molecules grab it). In moist air the water vapour moves into a H2O saturated air mass, saturated air mass has less free ports. So water vapour can drift away. Cirrus clouds form in cold air, they are wispy and thin because the electrochemical activity has slowed down and the electrons vibrate less. Electrons need to vibrate so as they can engage with each other. Or put simply heat and saturation govern chemical interaction.

[@PacificCircle1]

I would like to see researchers investigate the role of evaporation due to irrigation and deforestation. Such activates must increase water vapor, the primary Greenhouse gas.

[@alanmcintire8727]

+PacificCircle1 It's been done. journals.ametsoc.org/doi/abs/10.1175/JCLI3627.1 We get slightly cooler days thanks to plant transpiration, warmer nights, and an overall slight warming.l

[@PacificCircle1]

Alan Mcintire Thanks. That study was done in my region! Cool. What I should have said was the role of human induced humidity should be given more weight in the Climate Change discussions.

[@citizenschallengeYT]

Here's an UPDATE regarding the overall impact of clouds on Earth's heat budget: *Observational constraints on mixed-phase clouds imply higher climate sensitivity* Tan, Storelvmo, Zelinka | Science 08 Apr 2016: Vol. 352, Issue 6282, pp. 224-227 science.sciencemag.org/content/352/6282/224 also see: mobile.nytimes.com/2016/04/08/science/climate-models-may-overstate-clouds-cooling-power-research-says.html

[@markyoung8613]

Water vapour is only .04% of our atmosphere. So the cloud formation effect will be

[@112hidde112]

The contrails....

[@zzebowa]

"all these things have now happened" Sorry, that isn't true. Tropospheric warming has not been substantial enough, humidity has not increased (look at ALL data sets) and only one pole is warming.

[@diannemurray]

You claim it isn't true. But have you got any citations from peer-reviewed journals to back up your assertion? I see no reason to believe you over a professor on an accredited University's KZbin channel. You cpu;d be anyone. you could be being paid by oil companies for all the rest of us know. Pony up with the data or it's bullshit.

[@roger_is_red]

try listening because then you learn and will not come off as being so useless

[@zzebowa]

@@diannemurray NASA NVAP-M, ISCCP VW, there you go, no substantial VW increase

[@zzebowa]

@grindupBaker Lets say half the Claussius Clapeyron relationship

[@zzebowa]

@@roger_is_red Clouds cause cooling. Much of the warming since 1970 is due to clean air acts

[@markyoung8613]

Opps. looks like the 1'c has already happened, and the Ice shelves, Opps, Opps oh shite.