Table AIV-6.—WMO CODE 1677 WMO CODE 1677 h_sh_s - Height of base of cloud layer or mass indicated by genus C. h_th_t - Height of tops of low cloud or fog layer. * U.S. observers use the modified scale in feet. code meters feet code meters feet code meters feet code meters feet 00 <30 <100 25 750 2500 50 1500 5000 75 7500 25000 01 30 100 26 780 2600 51 - 76 7800 26000 02 60 200 27 810 2700 52 not 77 8100 27000 03 90 300 28 840 2800 53 - 78 8400 28000 04 120 400 29 870 2900 54 used 79 8700 29000 05 150 500 30 900 3000 55 - 80 9000 30000 06 180 600 31 930 3100 56 1800 6000 81 10500 35000 07 210 700 32 960 3200 57 2100 7000 82 12000 40000 08 240 800 33 990 3300 58 2400 8000 83 13500 45000 09 270 900 34 1020 3400 59 2700 9000 84 15000 50000 10 300 1000 35 1050 3500 60 3000 10000 85 16500 55000 11 330 1100 36 1080 3600 61 3300 11000 86 18000 60000 12 360 1200 37 1110 3700 62 3600 12000 87 19500 65000 13 390 1300 38 1140 3800 63 3900 13000 88 2 1000 70000 14 420 1400 39 1170 3900 64 4200 14000 89 >2 1000 >70000 15 450 1500 40 1200 4000 65 4500 15000 16 480 1600 41 1230 4100 66 4800 16000 17 510 1700 42 1260 4200 67 5100 17000 18 540 1800 43 1290 4300 68 5400 18000 19 570 1900 44 1320 4400 69 5700 19000 20 600 2000 45 1350 4500 70 6000 20000 21 630 2100 46 1380 4600 71 6300 21000 22 660 2200 47 1410 4700 72 6600 22000 23 690 2300 48 1440 4800 73 6900 23000 24 720 2400 49 1470 4900 74 7200 24000 AIV-13