Most commonly, patients describe acute tenderness in the buttock and sciatica-like pain down the back of the thigh, calf and foot. Typical piriformis syndrome symptoms may include: 1  A dull ache in the buttock. 2  Pain down the back of the thigh, calf and foot (sciatica).
We think of ice as snowflakes, ice cubes, snow cones, and dangerous patches on the sidewalk. Scientists have many different ways of categorizing ice too! There are actually fourteen types of ice that exist in different environments.
In 1971 a lake and river ice classification system was established by Bernard Michel and R Ramseier (ref 1,2) Primary Ice: The first ice that forms; Secondary Ice: Ice that forms under primary ice; Superimposed Ice: Typically snow ice and puddle ice on top of the ice sheet or frazil ice underneath. Agglomerate Ice: broken ice that refreezes into an ice sheet. Primary Ice is first thin layer to form.