Ship Driver Weather and Meteorology 2 — Questions and Answers
Question 1: What is the primary cause of radiation fog commonly encountered by mariners in coastal areas?
- Warm moist air moving over cold water
- Nighttime cooling of land causing moist air near the surface to reach its dew point (Correct answer)
- Cold air descending from higher altitudes over warm water
- Heavy rain evaporating before reaching the surface
Correct answer: Nighttime cooling of land causing moist air near the surface to reach its dew point
Radiation fog forms when land cools rapidly at night through radiative heat loss, chilling the moist air near the surface below its dew point, which can drift over nearby coastal waters.
Question 2: What is the minimum sustained wind speed that classifies a tropical cyclone as a 'tropical storm' in the Atlantic basin?
- 25 knots
- 34 knots (Correct answer)
- 45 knots
- 64 knots
Correct answer: 34 knots
A tropical cyclone is classified as a tropical storm when its maximum sustained winds reach 34 knots (39 mph); below that it is a tropical depression.
Question 3: What is a squall, and why should mariners be concerned about one?
- A gradual increase in wind over several hours preceding a cold front
- A sudden, brief but intense burst of wind often accompanied by rain or hail (Correct answer)
- A persistent area of calm found near the equator
- A localized area of dense fog near shore
Correct answer: A sudden, brief but intense burst of wind often accompanied by rain or hail
A squall is a sudden, sharp increase in wind speed lasting minutes, often accompanied by precipitation, and can cause dangerous sea conditions with little warning.
Question 4: What is the eye of a hurricane characterized by?
- The most violent winds and heaviest rainfall of the storm
- Calm or light winds, relatively clear skies, and warm temperatures (Correct answer)
- A wall of water surging ahead of the storm
- Continuous lightning and electrical discharges
Correct answer: Calm or light winds, relatively clear skies, and warm temperatures
The eye of a hurricane is a relatively calm, clear area at the center of the storm with light winds and even brief sunshine, surrounded by the intense eyewall.
Question 5: What does the Coriolis effect cause winds to do in the Southern Hemisphere?
- Deflect to the right of their direction of motion
- Deflect to the left of their direction of motion (Correct answer)
- Travel in straight lines without curving
- Increase in speed near the equator
Correct answer: Deflect to the left of their direction of motion
In the Southern Hemisphere, the Coriolis effect deflects moving air to the left, causing low-pressure systems to rotate clockwise (opposite to the Northern Hemisphere).
Question 6: What action should a mariner take if caught in a tropical storm with no safe harbor nearby?
- Head directly toward the storm center to minimize exposure time
- Heave to or run before the storm, keeping the storm on the starboard quarter in the Northern Hemisphere (Correct answer)
- Drop anchor in open water and wait for conditions to improve
- Increase speed to maximum to outrun the storm
Correct answer: Heave to or run before the storm, keeping the storm on the starboard quarter in the Northern Hemisphere
A common strategy in the Northern Hemisphere is to keep the storm on the starboard quarter while running before it, moving away from the dangerous (right) semicircle of the storm.
Question 7: Which VHF weather broadcast channel is used in the United States to receive continuous marine weather forecasts?
- Channel 16
- Channel 22A
- Weather channels WX1–WX7 (162.400–162.550 MHz) (Correct answer)
- Channel 9
Correct answer: Weather channels WX1–WX7 (162.400–162.550 MHz)
NOAA Weather Radio broadcasts continuous marine weather forecasts on dedicated VHF-FM frequencies from WX1 through WX7, separate from standard VHF marine channels.
Ship Driver Weather and Meteorology 2
What is the primary cause of radiation fog commonly encountered by mariners in coastal areas?