Section 5A: Weather Observation

Question 1

List the types of weather information useful to the mariner.

Question 2

List the instrumental and non-instrumental observations you may make as the officer of the watch.

Question 3

Briefly explain the principle behind the construction and operation of the aneroid barometer. State the corrections to be applied to the reading.

Question 4

Briefly explain the principle of operation and the function of the barograph.

Question 5

Briefly explain the construction and the operation of the hygrometer. Explain the principle behind its operation. State the two types.

Question 6

Familiarise yourself with the dew point and relative humidity tables available for use with the readings obtained from the two types of hygrometers. What is the reason for having different Dew Point tables for the two types?

Question 7

State two uses of the knowledge of the sea surface temperature to the seafarer.

Question 8

Briefly explain the Voluntary Observing Ships Scheme and the role and functions of associated parties.

Question 9

State the role of the Port Meteorological Officer.

Question 10

Code the following ship reports:
Ship: 3FRK; Position: 27°-35’N/98°-29’W; Course made good last 3 hours: 320° @ 15 knots; Visibility 20 km; Wind: 240° estimated at 16 knots; Pressure: 1026.8 hPa; Tendency: +6.4 hPa; Barograph trace: rising steadily.

GMT: 08d 06h 00m

Temperature: Dry 28.5° C, Wet 23.0° C, Sea 20.6° C

Clouds: Total 6/8 of sky, low clouds 4/8 of sky, base 1000 metres above sea, Sc not resulting from Cu, Dense Ns, Ci in hooks progressively invading sky.

Weather: Present – precipitation near but not at station. Past – Cloud covering more than half sky throughout and intermittent drizzle.

Sea: period 08 seconds, height 01 metre.

Swell: from 050°, period 10 seconds, height 02 metres.

Guidelines: First copy down the groups from the Weather Code book. Then fill in the numbers under each code letter as appropriate.