Page 186 - "Mississippi in the 1st Person" - Michael James Stone (Demo/Free)

HUMIDITY IN COLD WEATHER

Higher humidity means that their is a larger concentration of water in the air. Water has a high-
er specific heat compared to oxygen gas, thus it is able to more easily give off heat (or take it
away in the case of something feeling cold).

An everyday example of this is how diving into a pool that's just above 0 degrees Celsius feels
much much colder than being outside in 0 degrees. Similarly cold air with high humidity will
reduce the temperature of our bodies faster than air with low humidity.

Now let's take in to account wind. The movement of molecules. With more humidity in the air
the wind is more able to remove hot molecules from your body. So a humid wind will cool you
better than a dry wind. Anyone that lives in a place like Southern Arizona can tell you that
wind is no more than a hot blow dryer in your face during the summer.

Case in point on water that moves vs doesn't. A wetsuit uses water to insulate your body. So
more water around does not mean you will feel colder. It is the ability of those molecules to

remove that heat. Ie. The molecules need to be able to transport heat away from you.

There has been controversy over why damp cold air feels colder than dry cold air. Some be-
lieve it is because when the humidity is high our skin and clothing become moist and are better

conductors of heat, so there is more cooling by conduction.

The humid air in contact with your skin, since it has a higher moisture content, has a higher
specific heat and therefore requires more energy to heat it. Thus your skin feels colder as a re-

sult.

LAKE EFFECT BLIZZARDS HAVE LITTLE OR NO WARNING

A lake-effect blizzard is the blizzard-like conditions resulting from lake-effect snow. Under
certain conditions, strong winds can accompany lake-effect snows creating blizzard-like condi-

tions; however the duration of the event is often slightly less than that required for a blizzard
[2]
warning in both the US and Canada.
Wind shear

Directional shear is one of the most important factors governing the development of squalls;
environments with weak directional shear typically produce more intense squalls than those

with higher shear levels. If directional shear between the surface and the height in the atmos-
phere at which the barometric pressure measures 700 mb (70 kPa) is greater than 60 degrees,

nothing more than flurries can be expected.

In Outdoor remote locations Wind Shears are often not measured though passes, ridges, hills

and any impediment can focalize winds into a wind shear event.