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General Information, Facts & Tables
[Weather / Geology Scales]

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Overview

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The tables below list common weather and geographical classification scales.
 

Beaufort Weather Notation 

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The table below lists the Beaufort weather codes and their descriptions.
 

Symbol

Short Description

Long Description

b

Blue Sky

Not more the 1/4 of sky covered with cloud

bc

Blue Sky / Clouds

Blue sky and cloud in equal amounts

c

Cloudy

Not more than 1/4 sky showing blue

d

Drizzle

Light rain

e

Wet Air

Wet air without rain falling

f

Fog

Visibility range between 200m and 1000m

g

Gale Force Winds

Force 8 or 9 maintained for not less than 10 min

h

Hail

Hail

i

Intermittent prefix

Used in front of other symbols to denote intermittent

ks

Drifting Snow

Drifting snow

kz

Dust / Sand Storm

Dust storm or sand storm

l

Distant Lightning

Distant lightning

m

Mist

Mist

o

Overcast

Cloud completely covering the sky in a uniform thick layer

p

Showers

Showers

q

Squalls

Squalls

r

Rain

Rain

rs

Sleet

Rain and snow together or partially melted snow

s

Snow

Snow

t

Thunder

Thunder

tl

Thunderstorm

Thunderstorm

u

Ugly

Ugly or threatening sky

v

Pure Air

Unusually distant visibility

w

Dew

Dew

x

Hoar Frost

Hoar-frost

y

Dry Air

Less than 60% relative humidity

z

Haze

Visibility range between 1km and 2km

 

Beaufort Wind Scale

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The table below lists the Beaufort wind scale numbers, features and wind speed.
 

Number

Features

Wind Speed

Min

Max

0 (calm)

smoke rises vertically; water smooth

0.0

0.3

1 (light air)

smoke shows wind direction; water ruffled

0.3

1.5

2 (slight breeze)

leaves rustle; wind felt on face

1.6

3.3

3 (gentle breeze)

loose paper blows around

3.4

5.4

4 (moderate breeze)

branches sway

5.5

7.9

5 (fresh breeze)

small trees sway, leaves blown off

8.0

10.7

6 (strong breeze)

whistling in telephone wires; sea spray from waves

10.8

13.8

7 (moderate gale)

large trees sway

13.9

17.1

8 (fresh gale)

twigs break from trees

17.2

20.7

9 (strong gale)

branches break from trees

20.8

24.4

10 (whole gale)

trees uprooted, weak buildings collapse

24.5

28.4

11 (storm)

widespread damage

28.5

32.6

12 (hurricane 1)

widespread structural damage

32.7

36.6

13 (hurricane 2)

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36.7

41.1

14 (hurricane 3)

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41.2

46.0

15 (hurricane 4)

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46.1

51.0

16 (hurricane 5)

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51.1

55.9

17 (hurricane 6)

undefined

56.0

60.8

 

Fujita Tornado Scale

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The "Fujita" tornado scale is used to quantify the damage caused by the effects of a tornado.
 

Category

Description

Wind speed

Damage

F0

Gale tornado

64-116 km/h
40-72 mph

Light damage. Some damage to chimneys; branches broken off trees; shallow-rooted trees pushed over; sign boards damaged.

F1

Moderate tornado

117-181 km/h
73-112 mph

Moderate damage. Surface peeled off roofs; mobile homes pushed off foundations or overturned; moving autos pushed off the roads.

F2

Significant tornado

182-253 km/h
113-157 mph

Considerable damage. Roofs torn off frame houses; mobile homes demolished; boxcars pushed over; large trees snapped or uprooted; light-object missiles generated.

F3

Severe tornado

254-332 km/h
158-206 mph

Severe damage. Roofs and some walls torn off well-constructed houses; trains overturned; most trees in forest uprooted; heavy cars lifted off ground and thrown.

F4

Devastating tornado

333-419 km/h
207-260 mph

Devastating damage. Well-constructed houses leveled; structures with weak foundations blown some distance; cars thrown and large missiles generated.

F5

Incredible tornado

420-512 km/h
261-318 mph

Incredible damage. Strong frame houses lifted off foundations and carried considerable distances; automobile sized missiles thrown through the air; trees debarked.

 

Mercalli Earthquake Scale

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The table below lists the levels (intensities) of the "Mercalli" scale and their physical effects.
 

Intensity Level

Physical Effects

Intensity 0

Registered only by seismographs.

Intensity 1

Not felt by people except under ideal conditions.

Intensity 2

Felt by people at rest, small suspended objects swing.

Intensity 3

Felt by people indoors, standing cars may rock.

Intensity 4

Felt generally indoors, people awakened, windows rattled

Intensity 5

Felt generally, some falling plaster, windows broken.

Intensity 6

Felt by all, furniture moved, walking difficult.

Intensity 7

Moderate damage, felt in moving cars.

Intensity 8

Damage to weak structures.

Intensity 9

Total destruction of weak structures, ground fissures.

Intensity 10

Ground badly cracked, only strongest buildings survive.

Intensity 11

Few buildings survive, broad fissures, underground pipes broken.

Intensity 12

Total destruction, visible ground waves.

 

Torino Scale

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The "Torino" scale relates to the chance of a extra terrestrial object colliding with the Earth.
 

No

Quick Description

Description

0

Events having no likely consequences

The likelihood of a collision is zero, or well below the chance that a random object of the same size will strike the Earth within the next few decades. This designation also applies to any small object that, in the event of a collision, is unlikely to reach the Earth's surface intact.

1

Events meriting careful monitoring

The chance of a collision is extremely unlikely, about the same as a random object of the same size striking the Earth within the next few decades.

2

Events meriting concern

A somewhat close, but not unusual encounter. Collision is very unlikely.

3

Events meriting concern

A close encounter, with 1% or greater chance of a collision capable of causing localised destruction.

4

Events meriting concern

A close encounter, with 1% or greater chance of a collision capable of causing regional devastation.

5

Threatening events

A close encounter, with a significant threat of a collision capable of causing regional devastation.

6

Threatening events

A close encounter, with a significant threat of a collision capable of causing a global catastrophe.

7

Threatening events

A close encounter, with an extremely significant threat of a collision capable of causing a global catastrophe.

8

Certain collisions

A collision capable of causing localised destruction. Such events occur somewhere on Earth between once per 50 years and once per 100 years.

9

Certain collisions

A collision capable of causing regional devastation. Such events occur between once per 1 000 years and once per 100 000 years.

10

Certain collisions

A collision capable of causing a global climatic catastrophe. Such events occur once per 100 000 years, or less often.

 

Sea Conditions

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The table below describes the different sea conditions and their properties.
 

Description

Height (m)

Effect

Calm (Glassy)

0

No waves breaking on beach

Calm (Rippled)

0 - 0.1

No waves breaking on beach

Smooth

0.1 - 0.5

Slight waves breaking on beach

Slight

0.5 - 1.25

Waves rock buoys and small craft

Moderate

1.25 - 2.5

Sea becoming furrowed

Rough

2.5 - 4.0

Sea deeply furrowed

Very Rough

4.0 - 6.0

Sea much disturbed with rollers having steep fronts

High

6.0 - 9.0

Sea much disturbed with rollers having steep fronts (damage to foreshore)

Very High

9.0 - 14.0

Towering Seas

Phenomenal

over 14

Precipitous seas (experienced only in cyclones)

 

Wave Conditions

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The table below lists the terms used to describe the properties of waves.
 

Description

Wave Length (m)

Wave Frequency (sec)

Wave Height (m)

Low Swell

0 - 200

under 11

0 - 0.2

Long Low Swell

over 200

over 11

0.2 - 2.0

Short Swell

0 - 100

Under 8

2.0 - 4.0

Average Swell

100 - 200

Between 8 and 11

2.0 - 4.0

Long Swell (Moderate Height)

over 200

Over 11

2.0 - 4.0

Short Heavy Swell

0 - 100

Under 8

4.0 -

Average Length Heavy Swell

100 - 200

Between 8 and 11

4.0 -

Long Heavy Swell

Over 299

Over 11

4.0 -