Test 3 Flashcards by Benjamin Ferrell

The direction of surface wind is?

From high pressure towards low pressure deflected by earth’s rotation.

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Tropical cyclones normally form within which of the following?

5 degrees to 15 degrees

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According to Buys Ballot’s law, when an observer in the Northern Hemisphere experiences a northwest wind, the center of low pressure is located to the

northeast

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You are enroute from Puerto Rico to New York. A hurricane makes up and is approaching. If the wind veers steadily, this indicates that your vessel is

in the dangerous semicircle

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Low-pressure disturbances, which travel along the intertropical convergence zone are called

tropical waves

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The approximate distance to a storm center can be determined by noting the hourly rate of fall of the barometer. If the rate of fall is 0.08-0. 12 inches, what is the approximate distance to the storm center

80 to 100 miles

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What kind of weather would you expect to accompany the passage of a tropical wave?

Heavy rain and cloudiness

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Tropical cyclones are classified by form and intensity. Which system does not have closed isobars?

Tropical disturbances

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A tropical wave is usually preceded by

Good weather

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Ocean swells originating from a typhoon can move ahead of it at speeds near

50 knots

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The highest frequency of tropical cyclones in the North Atlantic Ocean occurs during

August, September, and October

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Recurvature of a hurricane’s track usually results in the forward speed

increasing

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You have determined that you are in the right semicircle of a tropical cyclone in the Northern Hemisphere. What action should you take to avoid the storm?

Place the wind on the starboard bow and hold that course.

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A line on a weather chart connecting places which have the same barometric pressure is called an

isobar

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A rapid rise or fall of the barometer indicates

a change in the present weather conditions.

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In the Northern Hemisphere, if your vessel is in a hurricane’s navigable semicircle it should be positioned with the wind on the

starboard quarter, hold course and make as much speed as possible.

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A phenomenon where the atmospheric pressure is higher than that of other surrounding regions is called

a high-pressure area; an anticyclone; or a “high”

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Cyclones tend to move

parallel to the isobars in their warm sectors

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The flow of air around an anticyclone in the Southern Hemisphere is

counterclockwise and outward

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The dangerous semicircle of a hurricane in the Northern Hemisphere is that area of the storm

to the right of the storm’s track

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You are located within a stationary high-pressure area. Your aneroid barometer is falling very slowly. This indicates a(n)

decrease in the pressure of the system

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In the Northern Hemisphere which semicircle of a hurricane is the navigable semicircle?

left

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The hurricane season in the North Atlantic Ocean reaches its peak during the month of

September

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As a high-pressure system approaches, the barometer reading

rises

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In the Southern Hemisphere the wind circulation in a high-pressure system rotates

counterclockwise and outward

The eye of a hurricane is surrounded by dense black cumulonimbus clouds which are called the

wall cloud

What enables you to estimate the bearing of a storm's center?

Buys Ballot's Law

The left half of the storm is called the navigable semicircle because

Both A and B A. the wind speed is decreased by the storm's forward motion. B. the wind tends to blow vessels away from the storm's track

The edge of a hurricane has overtaken your vessel in the Gulf of Mexico, and the northwest wind of a few hours has shifted to the west. this is an indication that you are located in the

navigable semicircle

The rise and fall of the ocean's surface due to a distant storm is known as

swell

How can you estimate the position of a tropical storm's center?

with a radio weather bulletin or weather fax using shipboard radar observe the wind direction and apply Buys Ballot's Law all of the above.

Which scale is used to estimate wind speed by observing sea conditions

Beaufort scale

You are steaming west in the North Atlantic in an extratropical cyclonic storm, and the wind is dead ahead. According to the Law of Buys Ballot, the center of low pressure lies to the

north

If it is impossible to avoid a hurricane in the Northern Hemisphere, the most favorable place to be when the storm passes is in

that half of the storm lying to the right of the storm's path

The navigable semicircle of a tropical storm in the South Indian Ocean is located on which side of the storm's track

Right

What is the direction of rotation of tropical cyclones, tropical storms and hurricanes in the Northern Hemisphere?

Counterclockwise and inward

What classification of tropical cyclones would have closed isobars, counter-clockwise rotary circulation, and sustained winds between 34 and 63 knots?

a tropical storm

The wind velocity is higher in the dangerous semicircle of a tropical cyclone because of the

wind circulation and forward motion of the storm

When is the peak of the hurricane season in the western North Pacific?

July through October

What is the average speed of movement of a hurricane prior to recurvature?

10 to 12 knots

You are in the Northern Hemisphere and a tropical wave is located 200 miles due west of your position. Where will the wave be located 24 hours later?

Farther away to the west

Atmospheric pressure at sea level is equal to

14.7 pounds per square inch 29.92 inches of mercury 1013.25 millibars All of the above

What kind of pressure systems travel in tropical waves?

low pressure

A hurricane is characterized by winds of

64 knots or greater

When within 300 miles of a named tropical storm or hurricane, it is standard practice to send weather reports every

3 hours

Anticyclones are usually characterized by

dry, fair weather

The wind circulation around a high-pressure center in the Northern Hemisphere is

clockwise and moving outward from the high

What is the FIRST sign of the existence of a well developed tropical cyclone?

An unusually long ocean swell

Which kind of conditions would you observe as the eye of a storm passes over your vessel's position?

Huge waves approaching from all directions, clearing skies, light winds, and an extremely low barometer.

In a tropical cyclone, in the Northern Hemisphere, a vessel hove to with wind shifting counterclockwise is

in the navigable semicircle

A slow rise in the barometric pressure forecasts

improving weather conditions

Generally speaking, in the Northern Hemisphere, when winds are blowing from between SE and SW the barometric reading

is somewhat lower than it would be for winds from a northern quadrant

Which of the following statements concerning frontal movements is TRUE?

A cold front generally passes faster than a warm front

If an observer in the Northern Hemisphere faces the surface wind, the center of low pressure is to his

right, slightly behind him

"Surface circulation" is another term for

wind in the lower troposphere

The Beaufort scale is used to estimate the

wind speed

The intensity of a hurricane as it reaches higher latitudes and cooler waters

decreases

What is the first visible indication of the presence of a tropical cyclone or hurricane?

an exceptionally long swell

The first cloud formations you can use to indicate the bearing of the center of a hurricane or tropical storm are

the point of convergence of the cirrus clouds

As a licensed Merchant Marine Officer you are expected to

obtain a weather forecast before setting out from port listen to weather forecast on the radio while enroute understand all broadcast weather warning information All of the above

You are steaming eastward in the North Atlantic in an extratropical cyclonic storm and the wind is dead ahead. According to the law of Buys Ballot, the center of the low pressure lies

to the south

Severe tropical cyclones (hurricanes, typhoons) occur in all warm water oceans except the

South Atlantic Ocean

In a tropical cyclone in the Northern Hemisphere, a vessel hove to with the wind shifting counterclockwise would be

in the navigable semicircle

Tropical storms and hurricanes are most likely to form in the Southern hemisphere during

January through March

What is the average speed of the movement of a hurricane following the recurvature of its track?

20 to 30 knots

You are in the Northern Hemisphere and a tropical wave is located 200 miles due east of your position. Where will the wave be located 12 hours later?

Nearby to the east

The dense black cumulonimbus clouds surrounding the eye of a hurricane are called

cloud walls

A generally circular low pressure area is called a

cyclone

You can determine if your vessel's position is in the dangerous or navigable semicircle of a hurricane by

Both A and B A. observing whether the wind is veering or backing B. plotting two or more recent storm positions from weather bulletins

The dangerous semicircle of a typhoon in the Southern Hemisphere is that area

to the left of the storm's track

Weather information is available from

commercial radio broadcast the Coast Gaurd on scheduled marine information broadcast VHF-FM continuous marine weather broadcast provided by the National Weather Service All the above

The process by which the temperature and/or moisture characteristics of an air mass changes is called

modification

You can expect frontal activity when two air masses collide and

there are significant differences between the temperature of each air mass

A gale is characterized by a wind speed of

34 to 47 knots

You are attempting to locate your position relative to a hurricane in the Northern Hemisphere. If the wind direction remains steady, but with diminishing velocity, you are most likely

on the storm track behind the center

If you are caught in the left semicircle of a tropical storm, in the Southern Hemisphere, you should bring the wind

on the port bow, and make as much way as possible

Weather systems in the middle latitudes generally travel from

west to east

Where is the dangerous semicircle located on a hurricane in the Southern Hemisphere

to the left of the storm's track

A barometer showing falling pressure indicates the approach of a

Low-pressure system

A boundary between two air masses is a

front

If you observe a rapid fall of barometric pressure you should

prepare for the onset of stormy weather with strong winds

A slow, gradual fall of the barometer indicates approaching

deteriorating or unsettled weather

In the Northern Hemisphere, the largest waves or swells created by a typhoon or hurricane will be located

forward and to the right of its course

If a weather bulletin shows the center of a low-pressure system to be 100 miles due east of you, what winds can you expect in the Southern Hemisphere?

South-southwesterly

In the Northern Hemisphere, when the center of a high pressure system is due east of your position, you can expect winds from the

south to east

A tropical storm is a tropical cyclone that generates winds of

between 34 and 63 knots

When your vessel is on the track but behind the storm's center the

Wind direction remains steady barometer rises wind speed decreases all the above

Swells that have outrun the storm are produced in the

right front quadrant

What indicates the arrival of a hurricane within 24 to 36 hours?

unusually good weather with above average pressures followed by a slow fall 0f 4 millibars in six hours.

In the Northern Hemisphere, you are caught in the dangerous semicircle of a storm with plenty of sea room available. The best course of action is to bring the wind on the

starboard bow and make as much headway as possible.

The atmosphere in the vicinity of a high-pressure area is called

anticyclone

That half of the hurricane to the right-hand side of its track ( as you face the same direction that the storm is moving) in the Northern Hemisphere is called the

dangerous semicircle

In the Northern Hemisphere, an area of counterclockwise wind circulation surrounded by higher pressure is a

low