Albedo

Сентябрь 3, 2022

Содержание

2. Albedo of water surfaces Albedo depends on the Sun altitude especially over water surface (roughness) 90°
3. Albedo of clouds Albedo depends on cloud depth Threshold Albedo also depends on cloud form. The
4. Altocumulus (Ac) http://www.clouds-online.com/index.htm Description: Grey cloud bundles, sheds or rollers, compound like rough fleecy cloud, which
5. Stratocumulus (Sc) Description: Cloud plaices, rollers or banks compound dark gray layer cloud. Origin: By turbulence.
6. Cumulus (Cu) Description: Heap cloud with flat basis in the middle or lower level, whose vertical
7. Albedo of clouds Albedo depends on cloud depth Albedo also depends on cloud form. The largest
8. Dependence of albedo (r), transmission (P), and absorption (A) functions on the Sun altitude. Albedo, r%
10. Addition to albedo of clouds Difference between albedo of a separate cloud r and albedo of
11. The rate of separate cloud albedo, r(n), can be explained by the fact that, at small
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Albedo of water surfaces
Albedo depends on the Sun altitude especially over

water surface
(roughness)

90°

20°

45°

5°

12%

35%

Dependence on the Sun altitude causes well-defined diurnal and annual variations of albedo

Annual variation of albedo

Minimal albedo – summer
Maximal albedo -- winter

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Albedo of clouds
Albedo depends on cloud depth
Threshold
Albedo also depends on cloud

form. The largest albedo is at Ac and Sc clouds. Ac – 73%; Sc – 64%; Cu – 52%

Cloud depth (∆h), albedo (r), and transmission function (P).

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Altocumulus (Ac) http://www.clouds-online.com/index.htm
Description:
Grey cloud bundles, sheds or rollers, compound like rough fleecy

cloud, which are often arranged in banks.
Origin:
By rise of an expanded air layer at the border of a rising zone.
By convection or turbulence within an unstable layer of the middle cloud level.
By transformation from Altostratus und Nimbostratus at lability or Cumulus and Cumulonimbus at stability.

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Stratocumulus (Sc)
Description:
Cloud plaices, rollers or banks compound dark gray layer

cloud.
Origin:
By turbulence.
By convection in unstable air layers, which are limited by a strong inversion upward.
By undulation in very damp air layers and usually at inversions.
From other clouds (Nimbostratus, Cumulus, Stratus)

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Cumulus (Cu)
Description:
Heap cloud with flat basis in the middle or

lower level, whose vertical development reminds of the form of towers, cauliflower or cotton.
Origin:
The Cumulus always indicates an instability to the layering of air with appropriate convection or turbulence.

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Albedo of clouds
Albedo depends on cloud depth
Albedo also depends on cloud

form. The largest albedo is at Ac and Sc clouds. Ac – 73%; Sc – 64%; Cu – 52%

Cloud depth (∆h), albedo (r), and transmission function (P).

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Dependence of albedo (r), transmission (P), and absorption (A) functions on

the Sun altitude.

Albedo, r%

Transmission function, P%

Absorption function, A%

Albedo of clouds also depends on Earth’s surface albedo (re). The stronger the re value, the larger the cloud albedo

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Addition to albedo of clouds
Difference between albedo of a separate cloud

r and albedo of a cloud layer rl.
“n” is cloud amount in decimal fractions, is albedo of cloud free atmosphere at the level of the possible cloud top.
From the experimental data the following formula has been obtained.
Here, rl%, and n in points.

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The rate of separate cloud albedo, r(n), can be explained by

the fact that, at small cloud cover (n<6 point), the distance between clouds is rather big, and separated clouds act in each cloud own way (not interacting with each other).

As amount of clouds increasing, the clouds start interacting. Radiation scattered by a cloud side reaches some other clouds, resulting in increasing of reflection.