Welsh Journals

0.6 aridity index. Moist climates have positive value of the mois- ture index while dry climates. have negative values. This index TABLE i. Climatic Types and Corresponding Moisture Indices. Climatic Type. Moisture Index A Perhumid ioo and above B4 Humid 80 to 100 B, Humid 60 to 80 B2 Humid 40 to 60 Bi Humid 20 to 40 C2 Moist Subhumid o to 20 Cx Dry Subhumid -20 to o D Semi-arid -40 to -20 E Arid -6o to -40 has been calculated for all climatological stations in Wales and the results have been used as the basis for constructing the map of moisture regions. The map demonstrates a wide variety of mois- ture conditions within Wales, though no dry climates are re- presented. Anglesey, Lleyn, Pembrokeshire, S.W. Gower, the Vale of Glamorgan (between Porthcawl and Cardiff) and the Welsh Borderland (all in the Humid B2 category) are the driest parts. At the other extreme, the distribution of the Perhumid type (A Figure 8 category) within the upland zone is quite extensive, but agrees well with the distribution of sphagum bogs. It is within this perhumid