Download Basic Navigation - 2008 (Bawtry) Air Cadets

Basic Navigation
Lecture 5
ACP32 Vol2
Basic Navigation
By the end of this lecture you should know:
 The 6 Major Air Masses
Major Air Masses
 The Earth’s atmosphere is constantly
moving as warm air rises, cold air descends
and the Earth spins.
 There are 6 Major Air Masses that influence
British weather.
Major Air Masses
Major Air Masses
 Arctic Maritime
 Originating in the very cold Arctic seas, picks up a
little moisture as it travels south. Typical weather
conditions are:
 Summer - Very cold with frequent heavy showers.
 Winter - Very cold strong north, north-easterly
winds. Heavy snow showers in north.
Major Air Masses
 Polar Continental
 Originates in Siberia. In southern Britain the weather is dry
as it has not crossed much water. In northern Britain the
air mass has travelled over the north sea, losing heat and
picking up moisture.
 Summer - Warm and dry, cloud free. East coast tends to
be cool and showery with coastal fog in the north.
 Winter - Sleet and snow showers in the north. Cold strong
east winds.
Major Air Masses
 Tropical Continental
 Originates in North Africa, warm air moves north over
Europe and has little opportunity to pick up water vapour.
Typical weather conditions are:
 Summer only - Very hot and dry, hazy with occasional
thunder storms.
Major Air Masses
 Tropical Maritime
 Originates in warm tropical oceans around the
equator. Brings warm and wet air. Typical weather
conditions are:
 Summer - Warm south-west winds. Low stratus
cloud over west coast.
 Winter - Stratus cloud, hill fog and drizzle. Warm
with prolonged rainfall.
Major Air Masses
 Returning Polar Maritime
 Originates in Canada as very cold, dry air. Initially
it moves south, gains warmth and moisture. By
the time it reaches the Britain. Typical weather
conditions are:
 Summer - Warm with squally showers and storms
inland.
 Winter - Stratus cloud. Showers in the western
mountains.
Major Air Masses
 Polar Maritime
 Originates in north Canada and Greenland, crosses the
Atlantic Ocean picking up water vapour before reaching
Britain. Typical weather conditions are:
 Summer - Cool winds, heavy showers, thunder storms in
mountains
 Winter - Heavy showers in west with snow in mountains.
Clear skies at night in the east giving frost.
Major Air Masses
1 Arctic
Maritime
2 Tropical
Continental
3 Returning
Polar
Maritime
4 Tropical
Maritime
5 Polar
Maritime
6 Polar
Continental