In the lower atmosphere, the available data points to
increasing water vapor content, but because of large variations in local humidity from day to night, from day to day, and from season to season, no - one currently knows exactly how much more water vapor is going into the air (IPCC Working Group 1 Assessment Report 4, Chapter 3, «Observations: Surface and Atmospheric Climate Change», page 273).
Increasing water vapor content decreases the dry adiabatic lapse rate what should be observed with increasing CO2 is a lower lapse rate from surface to cloud layer and increased lapse rate from cloud layer upward.
The assumptions of
increasing water vapor content from increased air temperature over water is not generally valid.
It's also pretty likely that the El Nino will bring some very damaging weather at various points, which will serve to remind us that flooding is something to respect and yes, fear, whether it's driven by El Nino or by
increasing water vapor content due to global warming.
An Earth - like planet tends to
increase its water vapor content as its mean temperature increases.
Venus succumbed early to a «runaway water vapor greenhouse,» in which
the increased water vapor content arising from increased temperature reached an end state with much of the ocean evaporated into the atmosphere.
Not exact matches
Most climatologists expect that on average the atmospheres
water vapor content will
increase in response to surface warming caused by the long - lived greenhouse gases, further accelerating the overall warming trend.
As the temperature rises,
water vapor evaporates at a higher rate, raising the
water vapor content of the atmosphere, further amplifying the the
increased greenhouse effect of the additional carbon dioxide.
The factors that determine this asymmetry are various, involving ice albedo feedbacks, cloud feedbacks and other atmospheric processes, e.g.,
water vapor content increases approximately exponentially with temperature (Clausius - Clapeyron equation) so that the
water vapor feedback gets stronger the warmer it is.
Predictions related to the impact of pinatubo, post 1984 trends, the «satellite cooling» mismatch, lgm tropical sst,
water vapor increases, ocean heat
content etc have all been made and verified within a short time period.
Specific humidity
content of the air has
increased, as expected as part of the conventional
water vapor feedback, but in fact relative humidity also
increased between 1950 and 1990, indicating a stronger
water vapor feedback than given by the conventional assumption of fixed relative humidity.
@zebra I think the extreme weather factor is all about the
increasing lower - tropospheric
water vapor content, which plays out in storms as a latent heat issue.
This
increased water vapor appears to be participating in the generation of PSCs which also affect the ztratospheric ozone layer with the introduction of denitritification (the formation of NAD and NAT) which reduces both the ozone
content and reduces the removal of chlorine in the polar regions.
Instead, they discuss new ways of playing around with the aerosol judge factor needed to explain why 20th - century warming is about half of the warming expected for
increased in GHGs; and then expand their list of fudge factors to include smaller volcanos, stratospheric
water vapor (published with no estimate of uncertainty for the predicted change in Ts), transfer of heat to the deeper ocean (where changes in heat
content are hard to accurately measure), etc..
Moreover, the
increase in atmospheric
water vapor content in the Arctic region during late autumn and winter driven locally by the reduction of sea ice provides enhanced moisture sources, supporting
increased heavy snowfall in Europe during early winter, and the northeastern and mid-west United States during winter.
The
water vapor content of the atmosphere rises by about 50 percent if atmospheric temperatures were to
increase by 5C and relative humidity remained constant.
This can be affected by warming temperatures, but also by changes in snowfall,
increases in solar radiation absorption due to a decrease in cloud cover, and
increases in the
water vapor content of air near the earth's surface.2, 14,15,16,17 In Cordillera Blanca, Peru, for example, one study of glacier retreat between 1930 and 1950 linked the retreat to a decline in cloud cover and precipitation.18
One of the most substantial climate changes in response to global warming is the
increase in atmospheric
water vapor content.
Redently scientists that have measured the
water vapor content of the atmosphere have deduce the amount of
water vapor increase has been about 1 % per year over the past ten years.
An
increase in
water vapor content in the lower atmosphere would also reduce the cooling rate at night.
[Poitou & Bréon] IPCC has foreseen an
increase of the
water vapor content of the air and this has been observed.
In fact, since 1980 (the start of the data analyzed), an overall
increase in stratospheric
water vapor content as been responsible for perhaps 15 % of the overall temperature
increase.
Elliott et al. conclude, based on the selected data below 500 hPa only that SH (moisture
content)
increased slightly with warming, but not at a rate sufficiently strong to maintain constant RH, as is assumed by the IPCC models in estimating
water vapor feedback.
Moreover, the
increase in atmospheric
water vapor content in the Arctic region during late autumn and winter driven locally by the reduction of sea ice provides enhanced moisture sources, supporting
increased heavy snowfall in Europe during early winter and the northeastern and midwestern United States during winter.
The long - range NOAA observations show that both RH and SH (
water vapor content) have decreased as temperature has
increased.