CLOUDS AND CLOUD-DRIFT 2$ 



east in summer. This variation is in direct accordance with 

 the diminution of the anticyclone in winter, and the low 

 IDressure over the North American continent in summer ; and 

 it is difficult to understand why the wind at the latter place 

 hardly shows this variation.* 



It is in this stratum of moving air that the thunderstorm 

 cumuli are borne along, so that this stratum must reach at 

 least 5 or 6 miles above the surface ; and it is curious to 

 watch the heavy thunder-showers at Lucea sweep up from 

 the south-east in the summer months w^liile the sea-breeze is 

 often blowing hard from the north-east. 



At sea this easterly trade-wind moves at the rate of about 

 240 miles per diem ; at the Kempshot observatory this rate is 

 reduced to 142 miles per diem. 



There are still two higher currents of air shown by the 

 upper cloud-drifts, to which reference will be made in the 

 following section. 



Clouds and Cloud=drift 



There has been considerable confusion among writers on 

 Meteorology in the naming and classification of clouds. Early 

 in the nineteenth century Luke Howard proposed a system 

 based upon the thi'ee primary forms cirrus, cumulus, stratus, 

 and their compounds cirro-stratus, and so on ; and probably 

 it was the w^ant of proper definitions of the forms and com- 

 pound forms which led to the confusion. 



Recently there has been an international movement to- 

 wards uniformity in cloud nomenclature based upon Howard's 

 system ; and the International Committee have published a 

 valuable cloud atlas. It is therefore advisable to state what 

 clouds have hitherto been registered in Jamaica. 



Between 1880 and 1895 the Weather Service in Jamaica 

 followed the Instructions to Ohservers of the United States 

 Signal Service 



" Clouds will be recorded on a scale of from zero to ten, 

 zero being clear, and ten cloud}^ 



* Mr. E. Johnstone suggests tlie Blue Mountain range to the north of the 

 Plantation, the range running east and west. 



