It's a little confusing, but there are really only three main types.
A World of Winds
Although winds can be something between annoying and destructive
at times, without them the world would be a much less liveable
place.
Because winds are the main way that temperatures are modified over
the earth's surface. Otherwise the tropics would be unbearably
hot, the poles unbelievably cold, and the area in the middle
impossibly changeable.
But fortunately, winds and a number of other physical forces
combine to make this world a pleasant place to live, at least
most of the time.
So most of the weather we experience is accompanied by winds,
some typical of the weather system of the moment, some
developing at the boundary between two weather systems, and
some occurring as the next weather system takes over.
These winds occur within and at the boundaries of air masses -
extensive bodies of air with similar properties, and differing
from their neighbouring air masses with different properties.
To put it slightly differently, air masses are large bodies of
air which develop over different parts of the world. They can be
cold or warm, moist or dry, and at home over maritime or
continental regions. As the seasons come and go they expand and
contract as they interact with each other, and they can begin to
move, start to mix, and become a little wild at their boundaries,
often influenced by the rapid high altitude jet stream winds.
Behind the air masses and their movement is a more general attempt
by the atmosphere to equalize differences in temperature and air
pressure over the earth's surface. The two are strongly linked,
with warm air tending to rise, forming lower pressure areas, and
cold air sinking to form zones of high pressure. Air will move
from high pressure to low pressure, and this air movement gives
us our winds.
But it is not just air masses. Within them and at their boundaries
large and powerful weather systems form and travel over the
earth's surface, most commonly in a west to east direction, and
again the energy contained in them is largely redistributed by
winds.
In many parts of the world different types of winds regularly
occur at the same places, often around the same time of year, and
in many instances these winds have been given local names, like
the Chinook or Mistral. Almost every part of the world has its
own local winds with their own local names - they may be
welcomed or feared depending on their character, but they are
never ignored.
And it is these winds that are the subject of this article.
But before considering them, let's narrow the field a little.
Firstly we'll leave out the local winds such as sea breezes which
regularly develop on summer afternoons on lake and sea shores.
Some of these have their own local names, sometimes ending with
"Doctor" in recognition of the relief they give from a hot day.
Neither will we consider the weather systems which have earned
their names, often from the direction they come from, such as
the North American Nor'easters, Alberta Clippers and Pineapple
Expresses.
We can also leave out the seasonal weather events such as
Monsoons and Trade Winds, although they may have local named
winds forming part of the overall cycle. We'll also drop the
worldwide high altitude jetstream winds.
And we can also exclude the most severe winds of all, the
tornadoes, downbursts and hurricanes which are less predictable
and more erratic in their distribution. Although it is worth
noting that the names Hurricane and Typhoon were
originally local names, as are the less well known names for
the same weather systems, now sadly out of use, from Australia
- Willy Willy and Cock Eyed Bob.
So, onto the world's local winds.
Firstly, there are many of them. A good starting point is Golden
Gate Weather's Names of Winds, but the list is by no means complete.
The situation becomes much clearer when it is apparent that almost
all of them fit into three categories, because the weather
conditions which create a notable wind in one place are usually
repeated in other parts of the world.
The three categories are
Foehn winds - warm dry
winds descending from mountain ranges
Outflow Winds - cold winds blowing outwards from an
area, often an elevated plateau, of cold dry air usually forming
part of a high pressure system. Because these winds can be
stronger in and near mountain passes they are sometimes called
Gap Winds.
Pre-frontal Winds - dry, hot and often dust laden
winds which blow in advance of a frontal system. They can be
very strong and unpleasant, and may be followed by thunderstorms
and a change to cooler winds as they pass through.