GB/T 33673-2017 English PDF (GB/T33673-2017)

GB/T 33673-2017: Grade of horizontal visibility
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GB/T 33673-2017
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 07.060
A 47
Grade of Horizontal Visibility
水平能见度等级
ISSUED ON. MAY 12, 2017
IMPLEMENTED ON. DECEMBER 1, 2017
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of
China.
3. No action is required - Full-copy of this standard will be automatically and
immediately delivered to your EMAIL address in 0~60 minutes.
Table of Contents
Foreword ... 3 
1 Application Scope ... 4 
2 Terms and Definitions ... 4 
3 Grade of Horizontal Visibility ... 4 
Bibliography ... 5 
Foreword
This Standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This Standard was proposed by China Meteorological Administration.
This Standard shall be under the jurisdiction of the National Standardization Technical
Committee on Meteorological Disaster Prevention and Reduction.
The drafting organization of this Standard. Hebei Xingtai Meteorological Bureau.
The main drafters of this Standard. Yang Yongsheng, Wang Congmei, Zhang Yingxin,
Liu Jin.
Grade of Horizontal Visibility
1 Application Scope
This Standard specifies the grade of horizontal visibility.
This Standard applies to the monitoring, forecasting and services of horizontal visibility.
2 Terms and Definitions
For the purposes of this document, the following terms and definitions apply.
2.1
horizontal visibility
meteorological visibility
The maximum horizontal distance of target objects (black, of moderate size) seen or
recognized by a person with a normal eyesight from the sky background under the
weather conditions at that time; at night, it refers to the maximum horizontal distance
of illuminants of moderate strength which can be seen and recognized.
NOTE The minimum brightness contrast (contrast threshold) which is perceptible by the eyes
of a person with a normal eyesight is 0.05.
3 Grade of Horizontal Visibility
The grades of horizontal visibility include grade 1 ~ grade 6. The range of visibility and
qualitative term of each grade is shown in Table 1.
Table 1 – Grade of Horizontal Visibility
Grade Qualitative description term Horizontal visibility
1 Excellent V ≥ 10 km
2 Good 2 km ≤ V < 10 km
3 General 1 km ≤ V < 2 km
4 Relatively poor 500 m ≤ V < 1 km
5 Poor 50 m ≤ V < 500 m
GB/T 33673-2017
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 07.060
A 47
Grade of Horizontal Visibility
水平能见度等级
ISSUED ON. MAY 12, 2017
IMPLEMENTED ON. DECEMBER 1, 2017
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of
China.
3. No action is required - Full-copy of this standard will be automatically and
immediately delivered to your EMAIL address in 0~60 minutes.
Table of Contents
Foreword ... 3 
1 Application Scope ... 4 
2 Terms and Definitions ... 4 
3 Grade of Horizontal Visibility ... 4 
Bibliography ... 5 
Foreword
This Standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This Standard was proposed by China Meteorological Administration.
This Standard shall be under the jurisdiction of the National Standardization Technical
Committee on Meteorological Disaster Prevention and Reduction.
The drafting organization of this Standard. Hebei Xingtai Meteorological Bureau.
The main drafters of this Standard. Yang Yongsheng, Wang Congmei, Zhang Yingxin,
Liu Jin.
Grade of Horizontal Visibility
1 Application Scope
This Standard specifies the grade of horizontal visibility.
This Standard applies to the monitoring, forecasting and services of horizontal visibility.
2 Terms and Definitions
For the purposes of this document, the following terms and definitions apply.
2.1
horizontal visibility
meteorological visibility
The maximum horizontal distance of target objects (black, of moderate size) seen or
recognized by a person with a normal eyesight from the sky background under the
weather conditions at that time; at night, it refers to the maximum horizontal distance
of illuminants of moderate strength which can be seen and recognized.
NOTE The minimum brightness contrast (contrast threshold) which is perceptible by the eyes
of a person with a normal eyesight is 0.05.
3 Grade of Horizontal Visibility
The grades of horizontal visibility include grade 1 ~ grade 6. The range of visibility and
qualitative term of each grade is shown in Table 1.
Table 1 – Grade of Horizontal Visibility
Grade Qualitative description term Horizontal visibility
1 Excellent V ≥ 10 km
2 Good 2 km ≤ V < 10 km
3 General 1 km ≤ V < 2 km
4 Relatively poor 500 m ≤ V < 1 km
5 Poor 50 m ≤ V < 500 m