216 TV. MAREIOTT METEOEOLOGICAL 0BSEEVATI0N3. 



or overcast sky. It is also desirable to note the kind of cloud pre- 

 valent at the time, and the direction from which it is coming. 



The different modifications and forms of cloud are Cirrus, Cirro- 

 cumulus, Cirro-stratus, Cumulus, Cumulo- stratus, Stratus, and 

 ^^imbus. 



The Cirrus cloud consists of parallel veavy or diverging fibres 

 •which may increase in any or in all directions. It is that very high 

 cloud which looks like hair or feathers, and is formed of ice crystals. 

 The Cirro-cumulus is composed of small, well-defined, roundish 

 masses lying near each other, and quite separated by intervals of 

 sky. This cloud forms what is generally known as a "mackerel 

 sky." The Cirro-stratus consists of horizontal or slightly inclined 

 masses thinned towards a part of the circumference, bent down- 

 wards or undulated, and either separate or in groups. It is in 

 this cloud that halos and coronae are formed. The Cumulus is of 

 a convex or well-rounded shape, and is generally a cloud of the 

 day. The Cumulo-stratus is formed by the Cirro-stratus blending 

 with the Cumulus, either among its piled-up heaps, or spreading 

 underneath its base as a horizontal layer of vapour. The Stratus 

 is a widely extended continuous sheet of cloud, increasing from 

 below upwards. It is the lowest kind of cloud, its lower surface 

 commonly resting on the earth. The Kimbus is the well-known 

 rain-cloud, consisting of a cloud, or system of clouds, from which 

 rain is falling. 



In addition to the foregoing observations, it is very desirable to 

 note the state of the weather and any phenomena that may have 

 occurred since the last observation, such as thunder-storms, halos, 

 etc. These may be entered in the register in an abbreviated form 

 by the letters of Beaufort's notation, which is as follows : — 



p = passing temporary showers. 



q = squally. 



r = rain. 



s = snow. 



t = thunder. 



M = " ugly," threatening appearance 



of the weather. 

 V = visibility of distant objects. 

 w = wet, dew. 



b = blue sky. 



c = cloudy, but detached clouds. 

 d = drizzling rain. 

 / = foggy. 



g = dark, gloomy weather. 

 h = hail. 

 / = lightning. 



m = misty, hazy atmosphere. 

 = overcast, the whole sky beinjE 

 covered with an impervious cloud 



The hours of observation are 9 a.m. and 9 p.m., and must be 

 punctually attended to. The maximum and minimum ther- 

 mometers are to be read and set at 9 p.m., and the readings entered 

 to the same day. 



Omissions must be carefully avoided, otherwise the register will 

 be incomplete, and true means cannot be obtained ; it is, therefore, 

 necessary to have a deputy to take the observations in the absence 

 of the regular observer. 



