Weather
Fronts/Systems
Warm Front
A front can
best be described as the border between two different air masses. A warm front
is the leading edge of a milder or warmer air mass. A warm front travels in
such a way that it results in warm air replacing colder air. This happens as
the warm air rises up and over the cold air below. As the warm air travels
upwards, it begins to mix with the cold air aloft and condenses to form clouds.
You can usually expect periods of rain or drizzle for many hours as the front
approaches.
Cold Front
A cold front is
the leading edge of colder air. In front of it, you usually have warmer, more
humid air. Behind the front lies much cooler or colder and drier air. The cause
for cold fronts is colder air masses migrating southward from the polar
regions. It is part of the world's natural energy circulation or cycle, this is
how the earth "balances" out the warm and cold air masses around the
earth.High Pressure Centre
Indicates an
area of high pressure. In a high pressure system, air will slowly descend and flow out in a
clockwise direction at the ground. Normally a high will bring mainly sunny
skies to an area.
Low Pressure
Centre
Indicates an
area of low atmospheric pressure. In a low pressure system, air is flowing counterclockwise
into the centre of the Low. The air will rise and cool often resulting in
clouds and precipitation.
Trough
An elongated
area of low pressure.
Jet Stream
The jet stream
is like a current or river of air in the upper atmosphere, 7,000 to 13,000
meters up. It's created when cold and warm air masses come together. In the
mid-latitudes of the Northern Hemisphere winds will tend to move from the west
to the east. The jet stream, quite simply put, is the apex of these winds in
the upper atmosphere. The minimum criterion for jet stream speed is 93
kilometers per hour. The location and orientation of the jet stream changes
from day to day. Weather patterns are influenced by the position, strength and
orientation of the jet stream.
Acknowledgement: This information is derived from the following website.
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