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• open snow (includes snow on low vegetation) changes with age but is broadly ~0.85 for fresh snow to ~0.50 for old snow.  
• forest snow (snow beneath high vegetation) depends on vegetation type.  It is broadly ~0.3 just after a heavy snowfall  decreasing to ~0.2 after a few days due to snowmelt (for sufficiently warm temperatures) or wind drift (for cold temperatures).
• ice depends on snow cover but varies between ~0.7 with snow and ~0.4 without snow.
• melt ponds on otherwise extensive sea ice can reduce albedo locally.
• open water, lakes and sea is <0.1

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• due to tides that can cover and uncover extensive areas of sand or mud (e.g. around the Frisian Islands) or where the extent of a lake varies substantially during the year (e.g. Lake Kati Thanda–Lake Eyre, Australia).
• due to large areas of burnt vegetation after extensive forest fires.

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Fig2.1.4.6-1:  Example surface albedo as shown in the surface parameters charts.  The albedo is taken from climatological data on a monthly basis.

Solar noon is assumed when assigning model albedo values and so is probably an under-estimate of the true albedo for most of the time in daylight. 

 In the chartIllustration of the albedo field used by the model during the forecast:

• darker colours indicate the greater radiation absorption qualities of vegetation.
• lighter colours indicate areas of high reflectivity (snow over mountains and Russia, and from the sands of the Sahara), . Anomalous snowfall has not had an effect.
• the sea is shown blue with high absorption because it reflects back very little solar radiation. Solar noon is assumed when assigning model albedo values and so is probably an under-estimate of the true albedo for most of the time in daylight. 

See the current albedo chart.

Considerations

It is important to consider the effects of any day-to-day differences in albedo values between those deriving from actual conditions and those used in model forecasts.  

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• Albedo is not modified by the diurnal variation in solar zenith angle.
• Surfaces are assumed to be horizontal so no account is taken of land orientation or slope. 
• Differences in albedo that are not captured by the forecast (e.g. in mountainous areas or where observed conditions vary from forecasts).
• The albedo chart is purely climatological and anomalous conditions are not indicated.
• Albedo can be affected by melt ponds over polar sea ice sheets.
• Widespread anomalous snowfall (increase of albedo) or snowmelt (decrease of albedo) will change the heat energy available to the varying surfaces.
• Transitory local but significant variations in surface characteristics (e.g. extensive burnt vegetation, seasonal variation in lake extent) are not represented.
• Tides can cover and uncover extensive areas of sand or mud (e.g. around the Frisian Islands) or the extent of a lake can vary substantially during the year (e.g. Lake Kati Thanda–Lake Eyre, Australia).

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(Note: In older material there may be references to issues that have subsequently been addressed)

Read more on Albedo.

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Fig2.1.4.6-2: Example surface albedo as shown in the surface parameters charts.  The albedo is taken from climatological data on a monthly basis.

Solar noon is assumed when assigning model albedo values and so is probably an under-estimate of the true albedo for most of the time in daylight. 

 In the chart:

• darker colours indicate the greater radiation absorption qualities of vegetation.
• lighter colours indicate areas of high reflectivity (snow over mountains and Russia, and from the sands of the Sahara). Anomalous snowfall has not had an effect.
• the sea is shown blue with high absorption because it reflects back very little solar radiation.

See the current albedo chart.