![photo](images/visby_drill01.jpg)
The sky conditions have stayed the same since the last observation. Which present weather symbol and code best represents the situation?
Correct. Use weather code 02 when sky condition has not changed over the previous hour.
Incorrect. Use weather code 02 when sky condition has not changed over the previous hour.
![photo](images/visby_drill02.jpg)
Clouds have become further developed over the last hour. Which present weather symbol and code best represents the situation?
Correct. Use weather symbol 03 when clouds are increasing or showing further development.
Incorrect. Use weather symbol 03 when clouds are increasing or showing further development.
![photo](images/dust_storm_07.jpg)
Looking northward from your inland base, you can see sand suspended in the air. Winds are 12 knots from the west and you have not observed any strong gusts or whirls. Which present weather symbol best represents the situation?
Correct. Weather symbol 07 is used when no whirls or sandstorms are observed, but dust or sand is visible in the air at the time of observation. Encode blowing dust as BLDU and blowing sand as BLSA.
Incorrect. Weather symbol 07 is used when no whirls or sandstorms are observed, but dust or sand is visible in the air at the time of observation. Encode blowing dust as BLDU and blowing sand as BLSA.
![photo](images/arctic_ocean_fog_bank.jpg)
Some areas of fog are visible near the surface, but the vertical extent of the fog is not large. Which present weather symbol is used to describe this situation?
Correct. Use weather symbol 11 fog at the station with a vertical extent less than 30 feet at sea (or less than 6 ft over land) and covering only patchy areas. The visibility within the fog is less than 5/8 mi (0.55 nm or 1 km). Encode this as MIFG in your observation.
Incorrect. Use weather symbol 11 fog at the station with a vertical extent less than 30 feet at sea (or less than 6 ft over land) and covering only patchy areas. The visibility within the fog is less than 5/8 mi (0.55 nm or 1 km). Encode this as MIFG in your observation.
![photo](images/28_941285.jpg)
Twenty minutes ago, the fog that caused the visibility to drop to less than one-half mile lifted. Which symbol represents this situation?
Correct. Use weather symbol 28 for fog or ice fog that reduces visibility to less than 5/8 of a mile, ending in past hour. Encode this situation with FG for fog and FZFG for freezing fog.
Incorrect. Use weather symbol 28 for fog or ice fog that reduces visibility to less than 5/8 of a mile, ending in past hour. Encode this situation with FG for fog and FZFG for freezing fog.
![photo](images/34_173414.jpg)
No change is observed over the past hour during a sandstorm that has brought visibility down to 1/8 mi. Which symbol represents this situation?
Correct. Use weather symbol 34 when a sand or dust storm has reduced visibility to less than 5/16 mi (0.25 nm) and conditions have not changed in the last hour. Encode this situation with +SS for a sandstorm or +DS for a dust storm.
Incorrect. Use weather symbol 34 when a sand or dust storm has reduced visibility to less than 5/16 mi (0.25 nm) and conditions have not changed in the last hour. Encode this situation with +SS for a sandstorm or +DS for a dust storm.
![photo](images/36_lt_mod_blowing_snow.jpg)
Some snow is drifting just along the ground due to moderate surface winds. Which symbol represents this situation?
Correct. Use weather symbol 36 when snow if is being by the wind but only extending up to six feet. This is called drifting snow and is considered slight for visibilities lower than 6 nm, but not less than 5/8 nm and moderate for visibilities less than 5/8 mi but not less than 5/16 mi. Encode as either -DRSN or DRSN.
Incorrect. Use weather symbol 36 when snow if is being by the wind but only extending up to six feet. This is called drifting snow and is considered slight for visibilities lower than 6 nm, but not less than 5/8 nm and moderate for visibilities less than 5/8 mi but not less than 5/16 mi. Encode as either -DRSN or DRSN.
![photo](images/38_ilx-2.jpg)
Widespread blowing snow is occurring and reducing visibility to 1 mi. Which symbol represents this situation?
Correct. Use weather symbol 38 to describe blowing snow that reaches above eye level and and is considered slight (-BLSN) for visibilities lower than 6 mi , but not less than 5/8 mi, and moderate (BLSN) for visibilities less than 5/8 mi but not less than 5/16 mi. Encode this situation with -BLSN or BLSN.
Incorrect. Use weather symbol 38 to describe blowing snow that reaches above eye level and and is considered slight (-BLSN) for visibilities lower than 6 mi , but not less than 5/8 mi, and moderate (BLSN) for visibilities less than 5/8 mi but not less than 5/16 mi. Encode this situation with -BLSN or BLSN.
![photo](images/42_947549.jpg)
Fog has begun to thin over the last hour making the sky visible. Which symbol represents this situation?
Correct. Use weather symbol 42 to describe the situation when fog has become thinner in past hour and sky is now visible. Encode this situation with FG.
Incorrect. Use weather symbol 42 to describe the situation when fog has become thinner in past hour and sky is now visible. Encode this situation with FG.
![photo](images/43_363008.jpg)
Fog continues to cover the area and obscure the sky, but the visibility is slowly increasing. Which symbol represents this situation?
Correct. Use weather symbol 43 to describe fog that is thinning though the sky remains obscured. Encode this situation with FG.
Incorrect. Use weather symbol 43 to describe fog that is thinning but the sky is not visible. Encode this situation with FG.
![photo](images/46_159907.jpg)
Widespread fog has developed over the station during the past hour, but has not blocked out the sky. Which symbol represents this situation?
Correct. Use weather symbol 46 when foggy conditions are increasing with time and the sky is visible. Encode this situation with FG.
Incorrect. Use weather symbol 46 when foggy conditions are increasing with time and the sky is visible. Encode this situation with FG.
![photo](images/49_riming_fog_deck.jpg)
Rime ice is accumulating on nearby objects due to the presence of a fog layer that is obscuring the sky. Which symbol represents this situation?
Correct. Use weather symbol 49 for fog that deposits rime while obscuring the sky. Encode this situation with FZFG.
Incorrect. Use weather symbol 49 for fog that deposits rime while obscuring the sky. Encode this situation with FZFG.
![photo](images/visby_drill03.jpg)
Clouds in the area have begun dissipating over the last hour. Which present weather symbol and code best represents the situation?
Correct. Weather symbol 01 is used when clouds have become less developed or have begun dissipating over the last hour.
Incorrect. Weather symbol 01 is used when clouds have become less developed or have begun dissipating over the last hour.
![photo](images/nps_12267.jpg)
Nearby fires have led to significant reductions in air quality and visibility at your station. Which present weather symbol best represents the situation?
Correct. Weather symbol 04 is used in this situation when the visibility is reduced by smoke. Encode this as FU.
Incorrect. Weather symbol 04 is used in this situation when the visibility is reduced by smoke. Encode this as FU.
![photo](images/06_p1020978.jpg)
Calm to light winds have persisted throughout the day while dust has remained suspended in air. Which present weather symbol best represents the situation?
Correct. Weather symbol 06 is used when dust or sand is present, but has not been raised by the wind. Encode this the same as haze, HZ.
Incorrect. Weather symbol 06 is used when dust or sand is present, but has not been raised by the wind. Encode this the same as haze, HZ.
![photo](images/ship_in_fog.jpg)
Visibility is reduced to within 6 nm but is above ⅝ nm. Which present weather symbol is used to describe this situation?
Correct. Weather symbol 10 is used when visibility is greater than ⅝ mi (0.55 nm or 1 km) and less than 6 mi (5 nm or 10 km). Encode this as BR.
Incorrect. Weather symbol 10 is used when visibility is greater than ⅝ mi (0.55 nm or 1 km) and less than 6 mi (5 nm or 10 km). Encode this as BR.
![photo](images/Bratislava_Fog_2005_Nov_11.jpg)
Fog blankets the landscape and you can barely see a few hundred feet in front of you. The depth of the fog is less than 6 feet. Which present weather symbol is used for this situation?
Correct. Weather symbol 12 is used when fog is shallow (less than 6 feet on land or 30 feet at sea) but continuous. The visibility is less than 5/8 mi (0.55 nm or 1 km). Encode this as MIFG.
Incorrect. Weather symbol 12 is used when fog is shallow (less than 6 feet on land or 30 feet at sea) but continuous. The visibility is less than 5/8 mi (0.55 nm or 1 km). Encode this as MIFG.
![photo](images/30_390630.jpg)
A dust storm is occurring at the station that initially reduced the visibility to 5/16 mi. Conditions later improved. Which symbol represents this situation?
Correct. Use weather symbol 30 when a sand or dust storm has reduced visibility to less than 5/8 mi, but not less than 5/16 mi, and conditions have improved in the last hour. Encode this situation with SS for a sandstorm or DS for a dust storm.
Incorrect. Use weather symbol 30 when a sand or dust storm has reduced visibility to less than 5/8 mi, but not less than 5/16 mi, and conditions have improved in the last hour. Encode this situation with SS for a sandstorm or DS for a dust storm.
![photo](images/33_250642.jpg)
You are observing a dust storm that brought visibility down to 1/4 of a mile. Conditions have begun to improve. Which symbol represents this situation?
Correct. Use weather symbol 33 when a sand or dust storm has reduced visibility to less than 5/16 mi and conditions have improved in the last hour. Encode this situation with +SS for a sandstorm or +DS for a dust storm.
Incorrect. Use weather symbol 33 when a sand or dust storm has reduced visibility to less than 5/16 mi and conditions have improved in the last hour. Encode this situation with +SS for a sandstorm or +DS for a dust storm.
![photo](images/35_10400.jpg)
A sand storm has been increasing in intensity over the last hour and visibility is now 1/8 mi. Which symbol represents this situation?
Correct. Use weather symbol 35 when a sand or dust storm has increased in intensity and has reduced visibility to less than 5/16 mi (0.25 nm.) Encode this situation with +SS for a sandstorm or +DS for a dust storm.
Incorrect. Use weather symbol 35 when a sand or dust storm has increased in intensity and has reduced visibility to less than 5/16 mi (0.25 nm.) Encode this situation with +SS for a sandstorm or +DS for a dust storm.
![photo](images/39_mod_hvy_blowing_snow_above6ft.jpg)
Snow being blown by the wind extends well above eye-level, and has reduced visibility below 5/16 mi. Which symbol represents this situation?
Correct. Use weather symbol 39 to depict blowing snow that reaches above 6 feet and reduces visibility to below 5/16 mi. Encode this situation with +BLSN.
Incorrect. Use weather symbol 39 to depict blowing snow that reaches above 6 feet and reduces visibility to below 5/16 mi. Encode this situation with +BLSN.
![photo](images/41_237311.jpg)
Patchy fog has developed over the past hour. Which symbol represents this situation?
Correct. Use weather symbol 41 when fog begins to form in patches or increases over the previous hour. Encode this situation with FG.
Incorrect. Use weather symbol 41 when fog begins to form in patches or increases over the previous hour. Encode this situation with FG.
![photo](images/45_dense_fog_4829367_2660269981_z.jpg)
A dense fog has settled in, blocking out the sun and sky for over an hour. Which symbol represents this situation?
Correct. Use weather symbol 45 when fog intensity has not changed and the sky is not visible. Encode this situation with FG.
Incorrect. Use weather symbol 45 when fog intensity has not changed and the sky is not visible. Encode this situation with FG.
![photo](images/47_252589.jpg)
Foggy conditions have become worse over the past hour, blocking out the sky completely and grounding many flights. Which symbol represents this situation?
Correct. Use weather symbol 47 when fog is thickening and the sky is not discernable. Encode this situation with FG.
Incorrect. Use weather symbol 47 when fog is thickening and the sky is not discernable. Encode this situation with FG.
![photo](images/00_DI01528.jpg)
The sky is completely clear. Which present weather symbol and code best represents the situation?
Correct. When there is not a cloud in the sky, code 00 or an open circle is used to describe the weather conditions. Encode this as CLR or SKC.
Incorrect. When there is not a cloud in the sky, code 00 or an open circle is used to describe the weather conditions. Encode this as CLR or SKC.
![photo](images/hazy_runway.jpg)
Skies are mostly clear over the airport but haze has reduced visibility at low levels and air quality is poor. Which present weather symbol and code best represents the situation?
Correct. Weather symbol 05 is used in this situation when the visibility is reduced by haze. Encode this as HZ.
Incorrect. Weather symbol 05 is used in this situation when the visibility is reduced by haze. Encode this as HZ.
![photo](images/08_21364.jpg)
An isolated dust whirl is observed at the station. Which present weather symbol corresponds to this situation?
Correct. Weather symbol 08 is used for sand or dust that is picked up by whirls that are not part of a larger dust or sandstorm. This symbol works for features observed at or near the station. Encode this event using PO.
Incorrect. Weather symbol 08 is used for sand or dust that is picked up by whirls that are not part of a larger dust or sandstorm. This symbol works for features observed at or near the station. Encode this event using PO.
![photo](images/09_958084.jpg)
Since the last observation, a sandstorm was seen to the west of the station. Which present weather symbol should be used to describe this situation?
Correct. Weather symbol 09 is used for a dust or sandstorm was in the vicinity of the station within the last hour, but is not affecting the station at the observation time. Encode this using DS for dust storm and SS for sandstorm.
Incorrect. Weather symbol 09 is used for a dust or sandstorm was in the vicinity of the station within the last hour, but is not affecting the station at the observation time. Encode this using DS for dust storm and SS for sandstorm.
![photo](images/31_549082.jpg)
No change is observed for over an hour in a dust storm that is reducing visibility to ⅝ mi. Which symbol represents this situation?
Correct. Use weather symbol 31 when a sand or dust storm has reduced visibility to less than 5/8 mi, but not less than 5/16 mi, and conditions have not changed in the last hour. Encode this situation with SS for a sandstorm or DS for a dust storm.
Incorrect. Use weather symbol 31 when a sand or dust storm has reduced visibility to less than 5/8 mi, but not less than 5/16 mi, and conditions have not changed in the last hour. Encode this situation with SS for a sandstorm or DS for a dust storm.
![photo](images/32_96625.jpg)
A sand storm began in the last hour and visibility has dropped to half a mile. Which symbol represents this situation?
Correct. Use weather symbol 32 when a sand or dust storm has either begun or increased in intensity and has reduced visibility to less than 5/8 mi (0.55 nm), but not less than 5/16 mi (0.25 nm.) Encode this situation with SS for a sandstorm or DS for a dust storm.
Incorrect. Use weather symbol 32 when a sand or dust storm has either begun or increased in intensity and has reduced visibility to less than 5/8 mi (0.55 nm), but not less than 5/16 mi (0.25 nm.) Encode this situation with SS for a sandstorm or DS for a dust storm.
![photo](images/37_mod_hvy_blowing_snow_below6ft.jpg)
Snow is drifting below eye level, reducing visibility to about ¼ mi. Which symbol represents this situation?
Correct. Use weather symbol 37 to describe heavy drifting snow (to levels below 6 ft) where the visibility in the snow is below 5/16 mi. Encode this situation with +DRSN.
Incorrect. Use weather symbol 39 to describe heavy drifting snow (to levels below 6 ft) where the visibility in the snow is below 5/16 mi. Encode this situation with +DRSN.
![photo](images/40_125696.jpg)
Thick fog can be seen about 5 miles from the observing site. Which symbol represents this situation?
Correct. Use weather symbol 40 for fog that appears at a distance, but not at the station within the last hour. Encode this situation with PRFG (partial fog) or BCFG (patchy fog).
Incorrect. Use weather symbol 40 for fog that appears at a distance, but not at the station within the last hour. Encode this situation with PRFG (partial fog) or BCFG (patchy fog).
![photo](images/44_149644.jpg)
Fog occurring at the station has not changed in the last hour while sun and some patches of blue sky are still visible through the clouds. Which symbol represents this situation?
Correct. Use weather symbol 44 for fog conditions where the sky is visible and the conditions have not changed over the last hour. Encode this as FG.
Incorrect. Use weather symbol 44 for fog conditions where the sky is visible and the conditions have not changed over the last hour. Encode this as FG.
![photo](images/48_riming_fog_landscape.jpg)
Fog on a cold morning has deposited a layer of rime on nearby trees and objects while the sun and sky are visible. Which symbol represents this situation?
Correct. Use weather symbol 48 when fog is present and depositing rime ice and the sky is visible. Encode this situation with FZFG.
Incorrect. Use weather symbol 48 when fog is present and depositing rime ice and the sky is visible. Encode this situation with FZFG.