GB/T 35222-2017 in English

1. Standard Overview

GB/T 35222-2017 "Surface Meteorological Observation Specification Cloud" is an important standard in my country's meteorological observation field, mainly used to standardize the observation and recording methods of cloud shape, cloud amount and cloud height in surface meteorological observation. This standard is applicable to manual observation and aims to provide accurate basic data for meteorological scientific research, weather forecast and climate analysis.

2. Comparison of standard frameworks

3. Interpretation of the core content of the standard

3.1 Observation elements and definitions

The standard clearly defines the three core elements of cloud observation: cloud shape, cloud amount and cloud height.

• Cloud shape:Classification and description of clouds based on their appearance, structure, color, etc. is the basis of cloud observation.
• Cloud amount:Refers to the proportion of clouds covering the sky, which is recorded in two ways: total cloud amount and low cloud amount.
• Cloud height:Measurement of the vertical distance between the cloud base and the ground, which is an important indicator for judging weather systems.

3.2 Observation methods and techniques

The standard specifies a variety of cloud height measurement methods, including:

• Hydrogen balloon method: cloud height is measured by a balloon with a known ascent rate.
• Searchlight method: cloud base height is measured using elevation angle (formula: $h = l \times \tan\alpha$).
• Laser cloud meter: cloud height is calculated using light speed and reflection time (formula: $h = \frac{1}{2} \times C \times t \times \sin\alpha$).

• Cloud height is estimated based on cloud characteristics and empirical formulas (e.g. $h \approx 124(T - T_d)$).

4. Implementation Suggestions

4.1 Observation Site Construction

Meteorological observation stations should be located in areas with wide and unobstructed views to ensure that changes in the sky can be fully observed. For observation stations in high mountains or special terrains, special attention should be paid to the recording method of the relative position of the cloud base height to the ground.

4.2 Data Recording Specifications

Record strictly in accordance with the symbols and formats specified in the standard:

• The measured cloud height is marked with an "S" in the upper right corner of the value.
• No additional symbols are required for the estimated cloud height.
• When observing at night, pay attention to visual adaptability and combine starlight and weather phenomena to assist in judgment.

4.3 Data Quality Control

To ensure data accuracy:

• Regularly calibrate measuring instruments, such as laser cloud meters and searchlight equipment.
• Recorders need to receive professional training and master the characteristics and observation techniques of different cloud types.
• Establish a data review mechanism to ensure the integrity and consistency of observation data.