Plate 29-32 of 1921 cloud chart. 29. Anvil top of cumulo-nimbus (upper).
Mammato alto-stratus on underside of cumulo-nimbus overflow in vicinity of
tornado (lower). 30. Nimbus, with fog or stratus below. 31. Fracto-stratus (
right) under alto-stratus and cirro-straus, apparently from local thunderstorms.
32. Stratus clouds at two levels; one practically on the ground.