And even if you can demonstrate
an effect on cloud cover, clouds have both a cooling and a warming effect, what will the balance be and how much will that net forcing be?
Soot particles in the atmosphere absorb radiation, but studies suggest
their effect on cloud cover and thickness may promote an overall net cooling.
Have you ever considered the implications of solar wind and / or the lack of it having
an effect on cloud cover?
The reduction in nighttime cooling that leads to this bias may indeed be the result of human interference in the climate system (i.e., local effects of increasing greenhouse gases or human
effects on cloud cover), but through a causal mechanism different than that typically assumed.
When aerosol indirect
effects on cloud cover were included, tropospheric (anthropogenic) aerosol efficacy reduced from 1.14 to 0.99.
Not exact matches
At any given time,
clouds cover about 70 percent of the Earth's surface and together produce a net cooling
effect on the planet.
For a subset of 14 relatively clear (cloudy) stations, the mean temperature drop was 0.91 ± 0.78 (0.31 ± 0.40) degrees C, but the mean temperature drops for relatively calm and windy stations were almost identical, indicating that
cloud cover has a much greater
effect than wind
on the air temperature's response to an eclipse.
They change storm tracks,
cloud cover and other weather patterns, and they have devastating
effects on fisheries and other industries.
Located between the orbits of Mercury and Earth, Venus has a very thick atmosphere that is
covered by a layer of
clouds that produces a «greenhouse
effect»
on the planet.
A typical June Gloom morning consists of marine stratus
clouds covering the coast of southern California, [4] extending a varying distance inland depending
on the strength of the June Gloom
effect that day.
While
on the subject: Could I ask your take
on Erlykin et al. 2011, in particular their finding that any
effect of cosmic radiation is limited to 1 % of
cloud cover, and their estimate that any temperature increase due to such a mechanism over the past 50 years of barely changing CR is limited to 0.002 °C?
For cause and
effect: You never know, but I don't think that
cloud cover regulates the sun cycle... Globally, the variation of
cloud cover during a sun cycle is around 2 %, which can have a substantial influence
on global temperatures.
He conveniently ignores that decreased
cloud cover could be a result of the warming, executing a cause /
effect bait - and - switch
on us.
I have read more than one paper
on the topic, and my assessment is that
cloud cover and other water vapor
effects are widely recognized as among the biggest unknowns going forward.
[Response: These feedbacks are indeed modelled because they depend not
on the trace greenhouse gas amounts, but
on the variation of seasonal incoming solar radiation and
effects like snow
cover, water vapour amounts,
clouds and the diurnal cycle.
Unknown is what the overall
effect of greenhouse gases / temperature was / is / will be
on cloud cover.
During a sun cycle, the global
cloud cover changes with + / - 2 %, good for a change of several W / m2 (depending
on type of
clouds and region), far higher than the
effect of insolation change as result of the sun's energy variation.
Ever been out
on a cold clear night with the stars clearly visible, and then low
cloud cover comes in, and you experience a warming
effect?
These forcings are spatially heterogeneous and include the
effect of aerosols
on clouds and associated precipitation [e.g., Rosenfeld et al., 2008], the influence of aerosol deposition (e.g., black carbon (soot)[Flanner et al. 2007] and reactive nitrogen [Galloway et al., 2004]-RRB-, and the role of changes in land use / land
cover [e.g., Takata et al., 2009].
Finally I attempt a suggestion that perhaps one solution to the problem that the solar impact
on climate is underestimated by models might be because EBM and GCM, like GISS, do not contain CO2 and CH4 cycle mechanisms that might be partially
effected by the Sun, and other mechanisms are missing or uncertain (water vapor,
cloud cover, vegetation, bacteria respiration, UV radiation, cosmic ray
effects etc.).
LOL — Your claims global brightening from reduced
cloud cover is a climate forcing without considering the
effect of such
cloud cover changes
on outgoing IR.
This «climate sensitivity» not only depends
on the direct
effect of the GHGs themselves, but also
on natural «climate feedback» mechanisms, particularly those due to
clouds, water vapour, and snow
cover.
However, even a smaller figure (I had calculated about 0.17 W / m ^ 2 based
on your inflated figure for total planetary albedo, but you can check it out) is still significant when compared with the total flux imbalance, which I think is a more informative comparison than an arbitrarily selected change in
cloud cover, because it compares the sea ice reduction with the
effects of all climate variations that have been operating in recent years..
I propose a simple dependence of
cloud cover and water vapor greenhouse
effect on incident solar radiance which can maintains temperatures to 0.5 degrees over the last 4 billion years.
Radiative
effects of surface - observed
cloud cover anomalies, called «
cloud cover radiative forcing (CCRF) anomalies,» are estimated based
on a linear relationship to climatological
cloud radiative forcing per unit
cloud cover.
Every model assumes that tropical - region cirrus
cloud cover, which has a net warming
effect on surface temperatures, increases with increasing surface temperature — a positive feedback.
Given the small intrinsic
effect of CO2, it would only take a very small change in daily
cloud cover to completely cancel the CO2 absorption,
on the order of 2 %.
I've read most (but not all) comments and found nothing about the Svensmark
effect (cosmic ray influence
on cloud cover).
In this paper geographer Alexander von Danckelman describes the
effect of biomass burning in the Congo region
on visibility, haze,
cloud cover, and precipitation.
The cooling
effect of
clouds during the daytime depends very much
on solar inclination as well as
cloud optical thickness and
cover.
It's a survey — they look at the relationship between
cloud cover and GCR
on multiple levels as described in the recent literature, including during forbrush decreases, «positive cosmic ray excursions», over the 11 - year solar cycle, in the troposphere, the stratosphere, regional
effects, etc..
As the CO2 and CH4 (methane) level goes up, H2O vapour in the atmosphere falls which — because H2O is 30 times more important than CO2 as a «greenhouse gas» offsets the
effect of CO2
on temperature, while
cloud cover and albedo increases because warmed moist air rises to form
clouds, further cooling the world.
Climate models focus
on the
effect of greenhouse gases, primarily carbon dioxide and water vapor, to the neglect of
cloud cover.
(Note, however, that to the extent that positive
cloud feedbacks
on GHG - mediated forcing mediate a reduction in
cloud cover, the amplification will substitute some SW
effects for LW
effects due to the reduced
cloud greenhouse warming and increased warming from a lower albedo).
In my experience,
cloud cover has a much greater
effect on UHI than wind.
«Nature is too complex, they (the authors) say, and depends
on too many processes that are poorly understood or little monitored — whether the process is the feedback
effects of
cloud cover on global warming or the movement of grains of sand
on a beach,» the Times article explained.
A larger set of arrays in Mobile is tracking the
effect of heat and humidity
on solar production, and power pole - mounted panels in various locations are feeding energy to the grid in an experiment to gauge the
effects of frequent changes in
cloud cover.
We hear about «run - away» greenhouse
effect on Venus, without any explanation of how this is possible with 100 %
cloud cover if albedo and aerosols works as we think they do.
Chemically, there will be an increase in ozone depletion (due to increases in heterogenous surface chemistry in the stratosphere), increases in acid rain, possibly an increase in high cirrus
cloud cover due to indirect
effects of the sulphates
on cloud lifetime.
From solar influence weighting to % of white ground
cover to when are
clouds on the dayside VS lack of
clouds on the nightside, we have miles to go before gaining a good understanding of cause and
effect with climatology.
Apparently, the global average
cloud cover must not have a dramatic
effect on the global average clear - sky optical thickness..
The findings also show the
effect of reduced airborne particulates from burning coal, which may decrease the
cloud cover that cools the earth, probably has less of an impact
on climate through indirect cooling than originally projected.
Chemically, there will be an increase in ozone depletion (due to increases in heterogeneous surface chemistry in the stratosphere), increases in acid rain, possibly an increase in high cirrus
cloud cover due to indirect
effects of the sulphates
on cloud lifetime.
It's not very clear in the Kiehl and Trenberth energy budget diagram (Figure A. 1 in the El Niño's heat post) what the
effect of a change in
cloud cover on the various radiation components would be.
It could be human CO2, or unicorn farts, or cow farts (since cows are real), or plankton blooms, or the subtle
effect of sunbathing
on cloud cover.