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The alidade is mounted on a post at a height of 5 ft (1.5 m) from the ground. It consists of an arm with a pointer and open sight at one end and a rubber eyepiece at the other. The arm is mounted onto a curved scale that is marked both in meters and the coded cloud height (feet). The
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When the cloud is thin the beam of light may penetrate into the cloud. The observer should read the scale where the light first enters the cloud and not at the top. However, a remark may be made as to how far into the cloud the light was able to penetrate as this may be useful. In the case of
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observer looks through the eyepiece and sets the sight onto the spot projected on the cloud and reads the height from the attached scale.
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The projector is normally set at 90°, although 71° 31' may be used, in relation to the terrain. The projector consists of a 430-watt
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Department of
Transport (Canada) - Meteorological Branch - Ceiling Projectors and Associated Equipment - Manual 70
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conditions the observer should read the scale where the beam disappears.
55:(called the ceiling) above the ground. It is used in conjunction with an
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bulb set in a weatherproof housing. Inside the housing are two
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51:is used to measure the height of the base of
405:Meteorological instrumentation and equipment
153:meteorological equipment and instrumentation
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39:Alidade for use with a ceiling projector
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31:Interior of a ceiling projector
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23:Ceiling projector exterior
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234:Ice accretion indicator
274:Present weather sensor
101:Trigonometric function
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410:Cloud and fog physics
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199:Dark adaptor goggles
16:Meteorological tool
244:Lightning detector
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334:Thermo-hygrograph
324:Sunshine recorder
189:Ceiling projector
45:ceiling projector
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374:Whole sky camera
319:Stevenson screen
224:Heat flux sensor
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354:Weather balloon
349:Transmissometer
314:Sounding rocket
259:Pan evaporation
184:Ceiling balloon
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269:Pyrheliometer
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369:Weather vane
359:Weather buoy
249:Nephelometer
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151:Earth-based
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64:incandescent
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339:Thermometer
329:Tethersonde
309:Solarimeter
299:Snow pillow
264:Pyranometer
209:Disdrometer
49:searchlight
399:Categories
344:Tide gauge
289:Snow gauge
284:Rain gauge
279:Radiosonde
254:Nephoscope
229:Hygrometer
219:Field mill
194:Ceilometer
164:Anemometer
112:References
96:Ceilometer
294:Snowboard
214:Dropsonde
179:Barometer
174:Barograph
169:Atmometer
47:or cloud
384:Windsock
106:Triangle
90:See also
84:blizzard
204:Dewcell
68:mirrors
57:alidade
53:clouds
304:SODAR
239:Lidar
43:The
82:or
80:fog
401::
144:e
137:t
130:v
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