本文译自https://www.wmocloudatlas.org/observation-of-clouds-from-the-earths-surface-introduction.html
Observation of clouds from the earth's surface
(Section 2.7)
地基观云
Introduction
(Section 2.7.1)
引言
Observational conditions to which definitions of clouds apply
(Section 2.7.1.1)
适于判别云况的观测条件
The definitions of clouds given in the present Atlas apply, unless otherwise specified, to observations carried out under the following conditions:
除非特别指明，本云图集所定义的云况，适用于下述条件下所开展的观测：
(a) The observer is at the Earth’s surface, on land in areas without mountainous relief or at sea
- （1）观测者位于地球表面，在不是山地或海上的陆地上
(b) The air is clear, and no obscuring phenomena such as fog, haze, dust, smoke, etc. are present
- （2）空气通透，现场没有例如雾、霾、灰尘、烟雾等低能见度现象。
(c) The Sun is sufficiently high to provide the usual luminance and coloration
- （3）太阳足够高，能够提供平常的亮度和自然色彩。
(d) The clouds are so high above the horizon that the effects of perspective are negligible
- （4）云在地平线之上足够高，以至于透视的影响可以忽略不计。
It will be necessary to adapt the definitions to other conditions. In many cases this can easily be done; for example, by night when the Moon is in its brighter phases, it may play, with regard to the illumination of clouds, a role analogous to that of the Sun.
在其他情况下，相关定义作适当的改变是必须的。在很多情况下这很容易做到；例如，在晚上当月亮处于很亮的月相时，对于云的照度来说，月亮的作用与白天太阳的作用是相似的。
Steps in performing a cloud observation
(Section 2.7.1.2)
开展云观测的步骤
The following steps should be performed during a cloud observation:
在云观测活动中应当遵循下述步骤：
Estimate or measure total cloud amount (cover)
- 估测或测量总云量。
Identify all clouds in the sky by genus, and where possible species, varieties, supplementary features, accessory clouds, mother cloud and any other meteors associated with the cloud
- 按照云属以及与之相关的可能的云类、云种、附加特征、副云、主云和其他零散云，来判别整个天空的云况。
Estimate or measure cloud amounts of the individual cloud genera and cloud layers
- 估计或测量各云属和云层的云量。
Estimate or measure cloud height
- 估计或测量云高。
Estimate direction of movement
- 估计云的移动方向
