30.3.9 Sky Condition. In METAR, sky condition is reported in the format:
Amount / Height / (Type) or Indefinite Ceiling /
Height
30.3.9.1 Amount. The amount of sky cover is reported in eighths of sky cover, using contractions:
SKC clear (no clouds)
FEW >0/8 to 2/8 cloud cover
SCT scattered (3/8 to 4/8 cloud cover)
BKN broken (5/8 to 7/8 cloud cover)
OVC overcast (8/8 cloud cover)
CB cumulonimbus when present
TCU towering cumulus when present
NOTE.
1.
“SKC” will be reported at manual stations. “CLR” will be used at automated stations when no clouds below 12,000 feet are reported.
2.
A ceiling layer is not designated in the METAR code. For aviation purposes, the ceiling is the lowest broken or overcast layer, or vertical visibility into obscuration. Also, there is no provision for reporting thin layers in the METAR code. When clouds are thin, that layer shall be reported as if it were opaque.
30.3.9.2 Height. Cloud bases are reported with three digits in hundreds of feet. (Clouds above 12,000 feet cannot be reported by an automated station.)
30.3.9.3 Type. If towering cumulus clouds (TCU) or cumulonimbus clouds (CB) are present, they are reported after the height which represents their base.
EXAMPLE.
SCT025TCU BKN080 BKN250 . “two thousand five hundred scattered towering cumulus, ceiling eight thousand broken, two five thousand broken.”
SCT008 OVC012CB . “eight hundred scattered ceiling one thousand two hundred overcast cumulonimbus clouds.”
30.3.9.4 Vertical Visibility (indefinite ceiling height). The height into an indefinite ceiling is preceded by “VV” and followed by three digits indicating the vertical visibility in hundreds of feet. This layer indicates total obscuration.
EXAMPLE.
1/8 SM FG VV006 . visibility one eighth, fog, indefinite ceiling six hundred.
30.3.9.5 Obscurations are reported when the sky is partially obscured by a ground.based phenomena by indicating the amount of obscuration as FEW, SCT, BKN followed by three zeros (000). In remarks, the obscuring phenomenon precedes the amount of obscuration and three zeros.
EXAMPLE.
BKN000 (IN BODY) . “sky partially obscured.”
FU BKN000 (IN REMARKS) . “smoke obscuring five. to seven.eighths of the sky.”
30.3.9.6 When sky conditions include a layer aloft other than clouds, such as smoke or haze, the type of phenomena, sky cover, and height are shown in remarks.
EXAMPLE.
BKN020 (IN BODY) . “ceiling two thousand broken.” RMK FU BKN020 . “broken layer of smoke aloft, based at two thousand.”
30.3.9.7 Variable Ceiling. When a ceiling is below three thousand and is variable, the remark “CIG” will be shown followed with the lowest and highest ceiling heights separated by a “V.”
EXAMPLE.
CIG 005V010 . “ceiling variable between five hundred and one thousand.”
30.3.9.8 Second Site Sensor. When an automated station uses meteorological discontinuity sensors, remarks will be shown to identify site specific sky conditions which differ and are lower than conditions reported in the body.
EXAMPLE.
CIG 020 RY11 . “ceiling two thousand at Runway One One.”
30.3.9.9 Variable Cloud Layer. When a layer is varying in sky cover, remarks will show the variability range. If there is more than one cloud layer, the variable layer will be identified by including the layer height.
EXAMPLE.
SCT V BKN . “scattered layer variable to broken.”
BKN025 V OVC . “broken layer at two thousand five hundred variable to overcast.”
30.3.9.10 Significant Clouds. When significant clouds are observed, they are shown in remarks, along with the specified information as shown below:
a) Cumulonimbus (CB), or Cumulonimbus Mam-matus (CBMAM), distance (if known), direction from the station, and direction of movement, if known. If the clouds are beyond 10 miles from the airport, DSNT will indicate distance.
EXAMPLE.
CB W MOV E . “cumulonimbus west moving east.”
CBMAM DSNT S . “cumulonimbus mammatus distant south.”
b) Towering Cumulus (TCU), location, (if known), or direction from the station.
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：美国航行情报汇编 AERONAUTICAL INFORMATION PUBLICATION AIP 1(169)
