Meteorology Tutorial 2

1a)              For a TRS in southern hemisphere, draw plan showing isobars, wind direction, strength, vortex, trough line, path, navigable semi, dangerous quadrant.

b)           Draw a cross section showing air flow, areas of cloud and precipitation,

c)            Draw a typical path

d)                  Describe the necessary conditions for this to form

·              The latitude must be not less than 4° to 6°

·              Sea temp must be greater than 26 degrees.  Air near the surface must be saturated

·              There most be no vertical wind shear and conditions must allow upper divergence.

·              There must be no inversion layers to restrict formation of Cb clouds

·              There must be a pre existing disturbance: The source of which may be a trough of low pressure or islands producing more convection.

2a)              For a TRS in the northern hemisphere, draw a plan section showing isobars, wind direction, strength, vortex, trough line, track, navigable semi, and dangerous quadrant.

              List the typical signs that warn the mariner of the approach of a TRS.

·              Any waves where they are not expected.  I.e., large waves in fairly light winds. Waves travel at great speed away from the storm.

·              A change in intensity or direction of the trade winds.

·              Irregularity in semi diurnal variation of barometric pressure, or pressure being lower than 3 degrees than seasonal average.

·              oppressive atmosphere with increasing humidity.

·              An ugly or lurid sky at sunset or sunrise.

·              Cirriform clouds thick spiral bands

Pressure slowly falling              500 to 120 miles away.

Distinct fall                                          120 to 60 miles away.

Rapid fall                                          6 miles or less.

Sketch a typical path.

State two reasons why dangerous semi is so named.

·              This is the area of strongest winds. 

b)              ·              A vessel caught in here may be blown into the path of the storm, or the storm may

Re-curve over her.

c)            State the Beaufort wind associated with each of the following as defined by IMO.

Tropical Depression: - Winds are to be no more than force 7

Moderate tropical storm: - Winds to be in region of force 8-9

3.a)              List signs of approaching TRS in northern hemisphere.  See earlier.

b)     Draw a cross section through a TRS and use reference to this diagram to describe its wind and cloud structure.

c)            Explain the factors that cause decay of TRS.

·              TRS moves into higher latitude where water temperature is cooler and therefore supplies less energy.  TRS becomes an extra tropical depression.

·              TRS moves over Cold Ocean current and dies.

·              TRS makes landfall and weakens due to dry air and friction.

·              TRS moves into higher latitude where depression is forming and rapid deepening of this depression occurs.

4)                  State the local name for a TRS in the following areas.

In Bay of Bengal.                            Cyclone.

In Northern Australia.                            Cyclone or Willy Willy.

b)            State the Beaufort scale associated with each of the following.

Tropical Depression                            no greater than force 7

Severe Tropical Storm              Force 10 to 11

5)              List the signs that can warn the mariner of the approaching TRS.  See earlier.

Draw a cross section through a TRS and state size, wind, pressure trace and clouds.

b)            State Beaufort wind associated with the following.

Moderate Tropical Storm                            Force 8-9

Severe               Tropical Storm                            Force 10-11

Tutorial 4 (Climate)

1)            Describe the weather conditions in the following climatic zones.

N.E. trades.

·         The weather in the Trade Wind Zone is generally fair. 

·         Cumulus clouds tend to be small on the Eastern & Pole ward side of the zone and increase in size to the West and towards the Equator.

·         Rainfall tends to follow the same pattern.

·         On the Eastern side, fog and mist can form over the cold currents.

·         Haze is sometimes carried out to sea by offshore winds.

·         Winds are generally reliable Force 3-4 reaching maximum strength in spring.

The Doldrums.

·         As the Trade winds meet in this area, we can expect calm or light Easterly winds.

·         Huge Cumulonimbus clouds

·         Thunderstorms and Squalls.

·         Conditions are worse when the Trade Winds are strongest and when the trough is furthest from the Equator.

Sub-tropical high.

·         Lie between the Trade Winds and the Westerlies.

·         Generally light and variable winds.

·         Small amounts of cloud

·         Scanty Rainfall.

2)            Give a full description of the wx in Northern Indian Ocean in NE Monsoon.

·         October - March

·         Prevailing winds are N.E.’ly Force 4.

·         Generally fine and clear.

·         Clouds increasing towards the South

·         Rainfall increasing towards the South – considerable on the Eastern coast of Southern India and Sri Lanka

·         Visibility is generally good except in the North and East where smoke, dust and haze may occur.

3)            Compare Wx in Arabian Sea to Wx in China Sea during SW Monsoon.

During the SW Monsoon, air in the Arabian Sea is warm and moist. Wind may reach force 4-5 occasionally 7-8.  Weather is cloudy and unsettled with heavy rain on west coasts of India. 

In the China Sea winds are force 3-4.  There may be fog on the coasts of China, but off shore there may be good vis with about 4/8 cloud.

4)            Compare the weather in the Bay of Bengal in January and July.

Bay Of Bengal – January.

North Easterly winds F4

Small amounts of cloud although cloudy in the extreme South West of the Bay.

Considerable rainfall on South East coast of India and Eastern coasts of Sri Lanka.

Visibility is generally good except in the North because of smoke.

Bay Of Bengal – July.

South Westerly winds F4-5.

Generally cloudy except near the Eastern coasts of India & Sri Lanka.

Moderate around clouds except for above.

Tutorial 6

1)                  Describe the conditions in the upper atmosphere necessary for the formation of TRS.

There must be little or no vertical wind shear, and at high levels there must be an anti-cyclone in order that an outflow (divergence) takes place. 

2)                  Explain why the jet stream is detrimental to TRS formation.

If there are strong winds i.e. Jet Streams (Wind Shear), the high level outflow cannot become organised and the T.R.S. will not develop

3)                  Describe the differences likely to be found on upper air charts above a warm high and a cold high.

The cold high is a relatively shallow affair (perhaps 3 km) and an area of cold dense air near the surface produces the pressure.  A column of warm air extending upwards to a greater vertical extent on the other hand causes a warm high.  It is this that shows on the upper air charts.

4)         &#...