RAM PENETROMETER (AH: pp 143-148)

The ram profile is a record of a hardness index through a vertical section of the snowpack. The ram hardness (R) is measured by driving a ram penetrometer (ram or ramsonde) vertically into the snowpack. The ram is a tube or rod with a centimeter scale for depth and a standard cone-shaped tip. The opearator drops a hammer (H) a certain distance (f) and records the penetration depth (p) of the ram into the snow. These values are then used to calculate the ram hardness:

R = (nfH/p) + T + H

R is the ram hardness (Newtons)
n is the number of hammer blows (usually one) at that height and weight
H is the hammer weight (Newtons)
T is the weight of the ram (Newtons). Can change if you add additional sections.
f is the drop height of the hammer (cms).
p is the penetration depth of the ram into the snowpack (cms).

Usually the hammer weight and drop height are chosen such that the penetration depth is between 3 and 8 cm. The ram penetrometer readings are conducted from the top of the snowpack to the bottom. The ram hardness R is then plotted against depth.