Last Updated on 4 years by teboo
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050 07 00 00 PRESSURE SYSTEMS
050 07 01 00 The principal pressure areas
050 07 01 01 Location of the principal pressure areas
pressure and low-pressure areas in January and July.
Look at a diagram…
(02) Explain how these pressure areas are formed.
The ITCZ is isolation. Formed by the circulation up and down with divergence and convergence.
(03) Explain how the pressure areas move with the seasons.
Land masses warm up in the summer which bends the belts and also the sun relative to the Earth changes with the seasons and so does global circulation.
050 07 02 00 Anticyclone
050 07 02 01 Anticyclones, types, general properties, cold and warm anticyclones, ridges and subsidence
Warm
Blocking
Cold
Cold Temporary
Ridge maybe included here…
(02) Describe the effect of high-level convergence in producing areas of high pressure at ground level.
(03) Describe air-mass subsidence, its effect on the environmental lapse rate, and the associated weather.
Subsiding are warms at the DALR 3°per 1000′ which is faster than an average ELR. This warms up the air generally increasing stability as the ELR is still less so won’t rise.
(04) Describe the formation of warm and cold anticyclones.
Warm, sub tropical high belt and form from high level convergence.
Cold, formed over the poles from surface cooling for the air gets cooler and subsides.
(05) Describe the formation of ridges.
(06) Describe the properties of and the weather associated with warm and cold anticyclones.
Warm – poor vis, clear skies, warm dry surface, light winds.
Cold – Clear skies, cold dry surface and poor vis.
(07) Describe the properties of and the weather associated with ridges.
High pressure related weather amplified with stronger surface divergence.
(08) Describe the blocking anticyclone and its effects.
050 07 03 00 Non-frontal depressions
050 07 03 01 Thermal, orographic, polar and secondary depressions; troughs
Causes convergence at the surface. agin the air diverges quicker than it converges due to surface friction.
(02) Describe the formation and properties of thermal, orographic (lee lows), polar and secondary depressions.
Thermal – Intense heating – instability.
Orographic – Wind near the surface stopped by a mountain allowing colder air over the top with corresponding instability.
Polar depressions – Air from cold land masses blows over warmer sea, instability and severe weather.
Secondary depression, form within existing polar front depression or an additional mechanism such as orographic uplift.
(03) Describe the formation, the properties and the associated weather at troughs.
Elongated low pressure – isobaric trough.
Trough line – flows of air that become unstable – CBs, showers rain, gusts – shite.
050 07 04 00 Tropical revolving storms
050 07 04 01 Characteristics of tropical revolving storms
- Large body of water >26°C
- Unstable moist atmosphere with little vertical wind shear (can stop the uplift)
- Descent Coriolis effect needed so must be outside of 5° N/S
(02) State how a tropical revolving storm generally moves in its area of occurrence.
N – Moves west then turns NE
S – West then poleward to head SW at higher latitudes.
(03) Name the stages of the development of tropical revolving storms (tropical disturbance, tropical depression, tropical storm, severe tropical storm, tropical revolving storm).
Yep
(04) Describe the meteorological conditions in and near a tropical revolving storm.
- High winds
- Windshear
- Hail
- Icing
- Lightning
(05) State the approximate dimensions of a tropical revolving storm.
500km diameter (300nm)
(06) State that the movement of a tropical revolving storm can only rarely be forecast exactly, and that utmost care is necessary near a tropical revolving storm.
Ok then, I will.
050 07 04 02 Origin and local names, location and period of occurrence
(01) List the areas of origin and occurrence of tropical revolving storms, and their specified names (hurricane, typhoon, tropical cyclone).
(02) State the expected times of occurrence of tropical
revolving storms in each of the source areas, and their approximate frequency.
Above…