DWO Weather Assessment 2 — Questions and Answers
Question 1: A rapidly falling barometer of more than 1 mb per hour over several hours most likely indicates:
- Stable high pressure approaching
- An approaching storm system (Correct answer)
- Fair weather for the next 24 hours
- A stationary front overhead
Correct answer: An approaching storm system
A rapid pressure drop of more than 1 mb/hour sustained over several hours is a strong indicator that a storm system is approaching.
Question 2: On a weather map, isobars that are closely spaced together indicate:
- Calm winds and light breezes
- Strong pressure gradient and high winds (Correct answer)
- Warm air aloft and fog risk
- A stationary air mass
Correct answer: Strong pressure gradient and high winds
Closely spaced isobars represent a steep pressure gradient, which produces strong winds in the area.
Question 3: What type of fog commonly forms when warm, moist air moves over a cold ocean current?
- Radiation fog
- Advection fog (Correct answer)
- Frontal fog
- Steam fog
Correct answer: Advection fog
Advection fog forms when warm moist air is transported horizontally over a cooler sea surface and is cooled to its dew point.
Question 4: In the Northern Hemisphere, standing with the wind at your back, low pressure is located approximately:
- Directly behind you
- To your right and slightly behind
- To your left and slightly ahead (Correct answer)
- Directly in front of you
Correct answer: To your left and slightly ahead
Buys Ballot's Law states that in the Northern Hemisphere, with the wind at your back, low pressure is to your left.
Question 5: A vessel officer observes a halo around the moon at night. This is most commonly associated with:
- Clear and stable weather
- Approaching precipitation within 24-48 hours (Correct answer)
- Immediate thunderstorm threat
- Dense fog by morning
Correct answer: Approaching precipitation within 24-48 hours
A lunar or solar halo is caused by ice crystals in high cirrus clouds, which typically precede a warm front and incoming precipitation.
Question 6: Which wind scale is standard for reporting wind speed in maritime surface weather observations?
- Saffir-Simpson scale
- Beaufort scale (Correct answer)
- Fujita scale
- Enhanced Fujita scale
Correct answer: Beaufort scale
The Beaufort scale is the internationally recognized standard for estimating and reporting wind force at sea.
Question 7: What is the primary danger to vessels associated with a temperature inversion in the lower atmosphere?
- Extreme lightning activity
- Formation of waterspouts
- Reduced visibility due to fog or haze (Correct answer)
- Sudden wind shifts exceeding 45 knots
Correct answer: Reduced visibility due to fog or haze
Temperature inversions trap moisture and pollutants near the surface, suppressing mixing and leading to fog, haze, or smog that reduces visibility.
DWO Weather Assessment 2
A rapidly falling barometer of more than 1 mb per hour over several hours most likely indicates: