Getting in front of the white background – commonly known as garage door – in 4 inch (10cm) heels on an icy surface is one of the challenges being a style blogger in the sub-arctic in spring. In pressed snow, it is easy. The heel sinks in and you stand safely. Clear ice like you see in the above picture in front of the garage door, reacts to the pressure of body weight just by melting a thin film of ice. The quintessence is a dangerous slippy walk back and forth -supported by the strong arms of my photographer/husband. As soon as the pressure is released the water film freezes again. This phenomenon of melting upon pressure and refreezing as pressure is released is called regelation.
Here the force is my body weight times the acceleration of gravity, i.e. 50kg*9.81m/(s*s). Force also equals pressure times area. Doing a coarse estimate for pumps, we have all the body weight on about an area of 4in times 4in (4in=10cm=0.1m) when I stand on one foot. Thus, the area is 0.01 squaremeters. Rearranging for pressure provides 49050Pa. This pressure is about half the mean atmospheric pressure at sea level. However, most the time women put down the heel fist before going onto the ball of the foot. Then the pressure is on an area of 1 square centimeter, and the pressure yields 490 500 000Pa. This is when the regelation happens.
Regelation is why glaciers have meltwater even though temperatures are below 32F (0C). Regelation occurs for all substances that expand upon freezing. Water does do that. For such substances the melting point decreases with increasing (external) pressure. In the case of ice, the melting point decreases by 0.0072C per additional 100 000Pa of external pressure. This means for the pressure of my heels the ice melts at −3.5C or 33.8F.
The OOTD consist of my BF jeans, a denim shirt, cashmere short sleeve sweater, and pink quilted leather jacket. The pumps pick up the color of the sweater as do the dots on the socks. The outer outfit is my shearling motorcycle jacket and a Chinese silk scarf. A girlfriend of mine gave me this scarf as a gift when she came back from visiting her parents in China. I switched into my brown booties for better hold on the icy sidewalks.
Photos: G. Kramm (2014)
Copyright 2013, 2014 Nicole Mölders | All rights reserved