Where results make sense
About us   |   Why use us?   |   Reviews   |   PR   |   Contact us  

Topic: Cloud albedo

Related Topics

  EO Printall   (Site not responding. Last check: 2007-10-12)
Usually, the higher a cloud is in the atmosphere, the colder is its upper surface and the greater is its cloud greenhouse forcing.
The high, thin cirrus clouds in the Earth's atmosphere act in a way similar to clear air because they are highly transparent to shortwave radiation (their cloud albedo forcing is small), but they readily absorb the outgoing longwave radiation.
On the other hand, the longwave radiation emitted downward from the base of a stratocumulus cloud does tend to warm the surface and the thin layer of air in between, but the preponderant cloud albedo forcing shields the surface from enough solar radiation that the net effect of these clouds is to cool the surface.
earthobservatory.nasa.gov /Library/Clouds/printall.php   (1862 words)

 The influence of cosmic rays on terrestrial clouds and global warming
Also, because cloud formation processes probably differ in different meteorological regimes, such as pertain for instance over the tropics and the poles, and the cosmic ray flux is known to be dependent on magnetic latitude, we have examined the correlation between cloud factor and cosmic ray flux in different latitude zones, separately.
Thus, the low cloud albedo change, and the increase in solar irradiance which accompanies increasing solar activity, both operate to warm the climate and the respective radiative forcing contributions are compounded.
By analysing different low cloud types separately we found that clouds in a liquid phase account for almost all the variability during the observed period, leaving the ice clouds constant in time, except at the poles where a slight increasing trend for some of the ice cloud types is found.
www.solarstorms.org /CloudCover.html   (3870 words)

 Surface Albedo Under Clouds   (Site not responding. Last check: 2007-10-12)
Therefore, clouds tend to increase the proportion of radiation in that portion of the spectrum where snow/ice reflect most (the visible), so the broadband albedo increases under cloud cover.
A regression relationship was developed for estimating the cloudy sky surface broadband albedo of snow/ice based on the clear sky albedo, cloud optical depth, and the solar zenith angle.
The clear sky albedo is that retrieved for clear sky areas in an image and interpolated to cloudy areas.
stratus.ssec.wisc.edu /projects/albcloud/albcloud.html   (382 words)

 Interactions, Feedback Loops, and Arctic Weather Patterns
Because clouds have high albedo, more cloud cover will increase the earth's albedo and reduce the amount of solar radiation absorbed at the surface.
Another factor is whether the cloud albedo is higher or lower than that of the surface.
This is because the blanket effect of clouds tends to dominate over reductions in shortwave radiation to the surface caused by the high cloud albedo.
nsidc.org /arcticmet/patterns/feedback_loops.html   (381 words)

 The Impact of Ship-Produced Aerosols on the Microstructure and Albedo of Warm Marine Stratocumulus Clouds: A Test of ...
Stratus and stratocumulus clouds, which occur in persistent sheets covering large areas of the eastern parts of subtropical ocean basins, have relatively high albedo and therefore reduce the shortwave radiation received at the earth’s surface (Albrecht 1989).
The cloud base was close to 500 m, and cloud top was coincident with the top of the boundary layer, which was approximately 800 m deep and capped by a sharp temperature inversion (7 K).
In clouds with moderately high droplet concentrations the change in albedo associated with the reduced droplet size in the plume is small, since the albedo of these clouds was already high and hence their susceptibility to further change in albedo was low.
www.met.utah.edu /tgarrett/Publications/AerosolCloud/Durkee2000.html   (9731 words)

 IGAC | Measurements and Modeling of Atmospheric Methane Using Stable Carbon Isotopes
The indirect climatic effect of aerosols refers to the influence of aerosols on cloud optical depth and albedo, and cloud lifetime, as a result of anthropogenic changes in the number and composition of cloud condensation nuclei (CCN).
The large uncertainty attending indirect forcing exists because of the complex sequence of phenomena that connects aerosols with CCN, CCN with cloud droplets, and cloud droplets with cloud albedo and cloud lifetime.
Satellite data on mean cloud droplet radii in the Northern versus the Southern Hemisphere appear to reflect the effect of higher anthropogenic emissions of aerosols in the Northern Hemisphere [Han et al.
www.igac.noaa.gov /newsletter/17/cloud.php   (2133 words)

The combination of the cloud albedo effect and the cloud greenhouse effect acting together slightly cools the Earth's surface and the lower atmosphere (Ramanathan et al., 1989).
It is important to establish which physical properties of clouds are important to the climate system and relate the global climatology of these properties to their impact on radiation.
On the other hand, clouds form as a result of the atmospheric general circulation, which is driven by the radiative heating of the relatively warm regions (such as the surface of the Earth and the Tropics) and the net radiative cooling of the cold regions (such as the atmosphere and the polar regions).
asd-www.larc.nasa.gov /~yhu/paper/thesisall/node4.html   (1021 words)

 Pincus et al., 1999: Albedo bias and horizontal variability...   (Site not responding. Last check: 2007-10-12)
Estimates of cloud fraction from the two datasets are compared, and are in best agreement when a reflectance threshold between 0.09 and 0.10 is used.
Cloud fraction in scenes dominated by cumulus is much more sensitive to the reflectance threshold used for cloud detection than are scenes containing stratiform clouds.
The mean and dispersion of log optical thickness are related to cloud type: optical thickness increases as cloud type changes from cumuliform to stratiform, while the relative amount of variability decreases.
www.cdc.noaa.gov /people/robert.pincus/Papers/AlbedoBias   (343 words)

 GOES Operational Satellite Products
Cloud top pressure images describe the spatial variation of height and type of clouds over a region, and are useful for nowcasting and forecast-model data assimilation.
Cloud top pressure is derived using a method that correlates the cloud top temperature in an infrared window channel to a thermodynamic profile from the MM5 forecast model.
Surface albedo is the ratio of the radiation reflected by the surface to the incoming solar radiation, and an image of it describes the variation of the amount of solar radiation absorbed by the surface over a region.
wwwghcc.msfc.nasa.gov /goesprod/goesop.html   (627 words)

 Climate Analysis - Part 6
Clouds vary on all spatial scales from planetary down to about 30m, but practical considerations limit representation of cloud variability in global climate and weather models to spatial scales larger than about 100-300 km.
Figure 2 shows the annual average albedo bias, caused by neglecting the mesoscale cloud variability, where the bias is weighted by the cloud fraction to give a scene albedo bias.
The variability is caused by mixtures of different cloud types; the occurrence of upper-level clouds produces the larger effects.
isccp.giss.nasa.gov /climanal6.html   (452 words)

 Short-term Prediction Research and Transition Center
Cloud albedo is the fraction of solar radiation reflected directly by clouds in the atmosphere.
CTP is a measure of the height (in pressure units) for a given cloud or cloud layer of the highest level in the atmosphere at which the air contains a perceptible quantity of cloud particles.
Surface albedo is the ratio, expressed as a percentage, of the amount of radiation reflected by the earth's surface to the amount incident upon it.
www.ghcc.msfc.nasa.gov /sport/sport_glossary.html   (646 words)

 Term project
This albedo is defined as the ratio of the reflected short-wave radiation to incident short-wave radiation.
The albedo of surface depends on the following factors -- the type of surface, the solar elevation and the geometry of the surface relative to the Sun, and the spectral distribution of the solar radiation and the spectral reflection.
Usually clouds form when the water vapor in the air parcel is cooled and condensed to liquid form or when an air parcel is saturated with water vapor.
marine.rutgers.edu /cool/education/class/yuri/yuri.html   (2459 words)

 Wikinfo | Cloud
Clouds reflect all light and are white, but they can appear grey or even fl if they are so thick or dense that sunlight cannot pass through.
Clouds on other planets often consist of material other than water, depending on local atmospheric conditions (what gases are present, and the temperature).
The clouds tend to be wispy, and are often transparent.
www.wikinfo.org /wiki.php?title=cloud   (527 words)

 NASA GISS: Aerosol Workshop: Session 4   (Site not responding. Last check: 2007-10-12)
In view of the potential importance of the indirect (cloud) effects of atmospheric aerosols in radiative forcing, it is essential that studies be carried out to quantify these effects.
It exhibits the expected increase of droplet column concentrations between ocean and continental clouds and in tropical areas during dry seasons where biomass burning is prevalent.
Cloud susceptibility has been retrieved on a global scale and the result reveals that cloud susceptibilities around most continental areas are close to zero.
www.giss.nasa.gov /meetings/aerosols97/session4.html   (564 words)

 Pincus and Baker, 1994: Precipitation and cloud albedo susceptibility
Pincus and Baker, 1994: Precipitation and cloud albedo susceptibility
perturbation of clear sky reflectivity), the indirect effect (modification of cloud albedo), and the effect on the hydrologic cycle (modification of cloud thickness and horizontal extent).
We find that the sensitivity of cloud albedo to droplet number concentration (the "albedo susceptibility") is increased by 50-200% when the dependence of cloud thickness on particle number is included.
www.cdc.noaa.gov /people/robert.pincus/Papers/Susceptibility   (224 words)

 MISR: Introduction: Science Goals: Study of Clouds
The impact of clouds on sunlight ranges from the high reflectivity of thunderclouds, which may allow so little light to reach the surface that it seems the Sun has set prematurely, to the subtle, iridescent colors of sunlight transmitted through thin cirrus.
A wide variety of cloud properties must be taken into account: shapes, sizes, vertical and horizontal locations, lifetimes, numbers of liquid droplets of different sizes, numbers of ice crystals of different shapes and sizes, and more.
The effects of clouds on climate are so complicated that the leading climate models give conflicting answers regarding their impact of climate.
www-misr.jpl.nasa.gov /mission/introduction/goals3.html   (917 words)

 [No title]   (Site not responding. Last check: 2007-10-12)
Simultaneous in situ and satellite measurements are analyzed to detect the "fingerprints" of anthropogenic influences on cloud albedo over a dark land surface provided by a montane red spruce/Fraser fir ecosystem.
Cloud water samples underwent a preliminary analysis which consisted of a check of the pH with a standard pH probe and weighing of the sample.
Elevated levels of cloud water acidity for cases coincident with continental sector influence can be attributed to a combination of low pollutant aerosol emissions from Sector 3, as well as from the neutralizing impact of medium-to-high levels of alkaline soil aerosol particles such as calcium and magnesium ions.
nigec.ucdavis.edu /publications/ar/annual95/southeast/project13.html   (1396 words)

 Southeast Regional Center Director's Report   (Site not responding. Last check: 2007-10-12)
where h is the cloud thickness in m, N is the cloud droplet number concentration in m-3, w is the cloud liquid water content in g m-3 and [[rho]] is the density of liquid water (106 g m-3).
To determine the effect of pollution content on cloud albedo, twenty individual cases were appropriate for the calculation of cloud albedo from in situ measurements.
Cloud albedo determined from AVHRR data is compared with the albedo estimated from Equations (1) and (2) based on in situ microphysical measurements and is displayed in Figure 3 for four daytime cloud events.
nigec.ucdavis.edu /publications/ar/annual94/southeast/project15.html   (1887 words)

 ESRG TOGA COARE Data Distribution Site
The method accomplishes this by computing cloud albedo, the governing cloud parameter, from GMS VISSR measurements in the visible.
where Asat is the albedo measured at the satellite (the surface is assumed to reflect solar radiation isotropically), Bmin is the minimum brightness, a and a1 are direct and diffuse reflection coefficients, respectively, and a'o characterizes ozone absorption.
Depending on liquid water path, the ratio or narrowband to broadband albedo increases or decreases with sun zenith angle but the difference is small, in general.
www.crseo.ucsb.edu /esrg/toga/toga.html   (613 words)

 Climate Change 2001: The Scientific Basis
Indirect forcing by aerosols is broadly defined as the overall process by which aerosols perturb the Earth-atmosphere radiation balance by modulation of cloud albedo and cloud amount.
It can be viewed as a series of processes linking various intermediate variables such as aerosol mass, cloud condensation nuclei (CCN) concentration, ice nuclei (IN) concentration, water phase partitioning, cloud optical depth, etc., which connect emissions of aerosols (or their precursors) to the top of the atmosphere radiative forcing due to clouds.
Considering first remote sensing, satellite studies of clouds near regions of high SO emissions have shown that polluted clouds have higher reflectivity on average than background clouds (Kuang and Yung, 2000).
www.grida.no /climate/ipcc_tar/wg1/181.htm   (535 words)

 Pubs.GISS: Menon et al. 2002. 'Role of sulfate aerosols in modifying the cloud albedo: A closure experiment'   (Site not responding. Last check: 2007-10-12)
At a remote mountain-top location in the southeastern U.S., measurements were made to estimate the contribution of anthropogenic aerosols to the cloud albedo.
Cloud water sulfate content was used as a surrogate for anthropogenic pollution.
The cloud reflectivity inferred from satellite measurements and that calculated from in situ observations were found to vary with the cloud water sulfate and N. Non-linear increases in satellite inferred cloud albedo with LWP suggest the importance of determining the contribution of cloud dynamic feedbacks on the indirect effect.
pubs.giss.nasa.gov /abstracts/2002/MenonSaxena.html   (346 words)

 IGAC | The indirect radiative effect of aerosols
Perhaps the first to be recognized (and receive the most attention) is the albedo or “Twomey” effect—the increase in cloud albedo due to an increase in aerosol concentration.
The same processes that increase cloud albedo in low-level clouds (a production of more and smaller droplets) tend to decrease the efficiency with which precipitation is formed.
The same is true for the energy associated with this water—the latent heat released on condensation in clouds and the energy required for evaporation of water from the surface.
www.igac.noaa.gov /newsletter/23/noone.php   (1747 words)

 Plane-parallel biases computed from inhomogeneous Arctic clouds and sea ice
Monte Carlo simulations of the expected influence of nonuniformity in cloud structure and surface albedo on shortwave radiative fluxes in the Arctic atmosphere are presented.
The “absolute bias” is defined as the difference between the cloud albedo or transmittance for the uniform or plane-parallel case, and the albedo or transmittance for nonuniform conditions with the same mean cloud optical thickness and the same mean surface albedo, averaged over a given area (i.e., bias > 0 means plane-parallel overestimates).
We determine the sensitivity of the bias with respect to the following: domain averaged means and spatial variances of cloud optical thickness and surface albedo, shape of the surface reflectance function, presence of a scattering layer under the clouds, and solar zenith angle.
www.agu.org /pubs/crossref/2002/2002JD002092.shtml   (329 words)

The so-called Twomey effect (Twomey, 1977) is the enhancement of cloud droplet concentrations in response to increased numbers of condensation nuclei.
The result of this process is to increase the cloud reflectivity (albedo) for a given liquid water content.
Furthermore, quantitative relationships between the indirect forcing from clouds and anthropogenic aerosol inclusions have not been developed to a point where the even the prediction of cloud optical properties is reliable.
www.gs.howard.edu /atmosci/research/cloud.htm   (278 words)

 Level 2 Products and Algorithms   (Site not responding. Last check: 2007-10-12)
Depending on the surface albedo two different neural nets are used (one for surface albedo equal to zero, one for non-zero surface albedo).
Before processing the pixels as cloud, land or water, or to exempt them from further processing, it is necessary to screen and sort them into four categories: cloud, land, water, invalid.
Above land surfaces, TOA radiances are corrected for the spectral slope of the surface albedo prior to applying the algorithm.
earth.esa.int /envisat/dataproducts/meris/CNTR2-7.htm   (3826 words)

 MISR Level 2 Data Sets   (Site not responding. Last check: 2007-10-12)
MISR Level 2 Land Surface Data: bihemispherical and directional-hemispherical reflectance (albedo), hemispherical directional and bidirectional reflectance factor (BRF), BRF model parameters, leaf-area index (LAI), fraction of photosynthetically active radiation (FPAR), and normalized difference vegetation index on a 1.1 km grid.
MISR Level 2 TOA/Cloud Stereo Data: stereoscopically-derived cloud mask and cloud height on a 1.1 km grid, and reflecting level reference altitude on a 2.2 km grid.
Cloud motion parameters are calculated on a 70.4 km grid.
eosweb.larc.nasa.gov /PRODOCS/misr/products/level2.html   (247 words)

 Data @ NASA GISS: SeaWiFS Surface Solar Irradiance: DX Data Methods   (Site not responding. Last check: 2007-10-12)
Fill clouds for remaining points: during day, fill with the cloud fraction averaged during day if present, otherwise with the averaged during 24 hours of cloud fraction; during night, fill with the 24 hour average of cloud fraction.
The 24-hour cloud fraction was filled successively with the averaged E-W value, with the averaged N-S value, from yesterday, and from a filled zonal cloud fraction array (dependent on latitude and surface type).
Fill cloud optical thickness: obtain the missing optical thickness by applying the tau conversion table to the filled cloud albedo.
data.giss.nasa.gov /seawifs/dxdiff.html   (586 words)

Try your search on: Qwika (all wikis)

  About us   |   Why use us?   |   Reviews   |   Press   |   Contact us  
Copyright © 2005-2007 www.factbites.com Usage implies agreement with terms.