Sunny but cool
Good Morning Augusta.
This morning it is partly cloudy, then clear. High of 59F. Winds from the
NNW at 5 to 10 mph.
Tonight it will be clear, then mostly cloudy. Low of 37F. Winds less than 5
mph.
The readings outside right now, taken from my own weather instruments:
a relative humidity of 48% with a Dew Point of 24.1ºF.
The temperature is 40.2ºF with a very low wind chill.
Presently we have North Northeast winds between 4.3 mph and 11.0 mph.
Our Barometric pressure is 30.19 and rising with a weather graphic
indicating sun.
We had no precipitation overnight in this area.
Visibility is 10.0 miles with a great ceiling.
Since we had such gusty winds over the weekend, I thought I'd repost this
information about wind and how it is measured.
In measuring wind speed, we've all heard of the more common forms of
measurement – such as Mps=Meters per second, kmh=Kilometers per hour and
mph=Miles per hour. But exactly what does BFT stand for?
bft= Beaufort Wind Scale – it is an empirical measure that relates wind
speed to observed conditions at sea or on land. Its full name is the
Beaufort Wind Force Scale.
The scale was devised in 1805 by Sir Francis Beaufort, an Irish-born Royal
Navy Officer, while serving on HMS Woolwich. The scale that carries
Beaufort's name had a long and complex evolution, from the previous work of
others, including Daniel Defoe the century before, to when Beaufort was a
top administrator in the Royal Navy in the 1830s when it was adopted
officially and first used during Darwin's voyage on HMS Beagle.[1] In the
early 19th Century, naval officers made regular weather observations, but
there was no standard scale and so they could be very subjective - one man's
"stiff breeze" might be another's "soft breeze". Beaufort succeeded in
standardizing the scale.
The initial scale of thirteen classes (zero to twelve) did not reference
wind speed numbers but related qualitative wind conditions to effects on the
sails of a man-of-war, then the main ship of the Royal Navy, from "just
sufficient to give steerage" to "that which no canvas sails could
withstand."[2] At zero, all his sails would be up; at six, half of his sails
would have been taken down; and at twelve, all sails would be stowed
away.[3]
The scale was made a standard for ship's log entries on Royal Navy vessels
in the late 1830s and was adapted to non-naval use from the 1850s, with
scale numbers corresponding to cup anemometer rotations. In 1916, to
accommodate the growth of steam power, the descriptions were changed to how
the sea, not the sails, behaved and extended to land observations. Rotations
to scale numbers were standardized only in 1923. George Simpson, Director of
the UK Meteorological Office, was responsible for this and for the addition
of the land-based descriptors.The measure was slightly altered some decades
later to improve its utility for meteorologists. Today, many countries have
abandoned the scale and use the metric-based units m/s or km/h
instead,[citation needed] but the severe weather warnings given to public
are still approximately the same as when using the Beaufort scale.
The Beaufort scale was extended in 1946, when Forces 13 to 17 were added.
However, Forces 13 to 17 were intended to apply only to special cases, such
as tropical cyclones. Nowadays, the extended scale is only used in Taiwan
and mainland China, which are often affected by typhoons.
Wind speed on the 1946 Beaufort scale is based on the empirical formula:
v = 0.836 B3/2 m/s
where v is the equivalent wind speed at 10 metres above the sea surface and
B is Beaufort scale number. For example, B = 9.5 is related to 24.5 m/s
which is equal to the lower limit of "10 Beaufort". Using this formula the
highest winds in hurricanes would be 23 in the scale.
Today, hurricane force winds are sometimes described as Beaufort scale 12
through 16, very roughly related to the respective category speeds of the
Saffir-Simpson Hurricane Scale, by which actual hurricanes are measured,
where Category 1 is equivalent to Beaufort 12. However, the extended
Beaufort numbers above 13 do not match the Saffir-Simpson Scale. Category 1
tornadoes on the Fujita and TORRO scales also begin roughly at the end of
level 12 of the Beaufort scale but are indeed independent scales.
Note that wave heights in the scale are for conditions in the open ocean,
not along the shore.
Some other terms you may run across:
CI -- Current Intensity
MWS -- Mean Wind Speed
MSLP -- Mean Sea Level Atmospheric Pressure in Millibars
This morning it is partly cloudy, then clear. High of 59F. Winds from the
NNW at 5 to 10 mph.
Tonight it will be clear, then mostly cloudy. Low of 37F. Winds less than 5
mph.
The readings outside right now, taken from my own weather instruments:
a relative humidity of 48% with a Dew Point of 24.1ºF.
The temperature is 40.2ºF with a very low wind chill.
Presently we have North Northeast winds between 4.3 mph and 11.0 mph.
Our Barometric pressure is 30.19 and rising with a weather graphic
indicating sun.
We had no precipitation overnight in this area.
Visibility is 10.0 miles with a great ceiling.
Since we had such gusty winds over the weekend, I thought I'd repost this
information about wind and how it is measured.
In measuring wind speed, we've all heard of the more common forms of
measurement – such as Mps=Meters per second, kmh=Kilometers per hour and
mph=Miles per hour. But exactly what does BFT stand for?
bft= Beaufort Wind Scale – it is an empirical measure that relates wind
speed to observed conditions at sea or on land. Its full name is the
Beaufort Wind Force Scale.
The scale was devised in 1805 by Sir Francis Beaufort, an Irish-born Royal
Navy Officer, while serving on HMS Woolwich. The scale that carries
Beaufort's name had a long and complex evolution, from the previous work of
others, including Daniel Defoe the century before, to when Beaufort was a
top administrator in the Royal Navy in the 1830s when it was adopted
officially and first used during Darwin's voyage on HMS Beagle.[1] In the
early 19th Century, naval officers made regular weather observations, but
there was no standard scale and so they could be very subjective - one man's
"stiff breeze" might be another's "soft breeze". Beaufort succeeded in
standardizing the scale.
The initial scale of thirteen classes (zero to twelve) did not reference
wind speed numbers but related qualitative wind conditions to effects on the
sails of a man-of-war, then the main ship of the Royal Navy, from "just
sufficient to give steerage" to "that which no canvas sails could
withstand."[2] At zero, all his sails would be up; at six, half of his sails
would have been taken down; and at twelve, all sails would be stowed
away.[3]
The scale was made a standard for ship's log entries on Royal Navy vessels
in the late 1830s and was adapted to non-naval use from the 1850s, with
scale numbers corresponding to cup anemometer rotations. In 1916, to
accommodate the growth of steam power, the descriptions were changed to how
the sea, not the sails, behaved and extended to land observations. Rotations
to scale numbers were standardized only in 1923. George Simpson, Director of
the UK Meteorological Office, was responsible for this and for the addition
of the land-based descriptors.The measure was slightly altered some decades
later to improve its utility for meteorologists. Today, many countries have
abandoned the scale and use the metric-based units m/s or km/h
instead,[citation needed] but the severe weather warnings given to public
are still approximately the same as when using the Beaufort scale.
The Beaufort scale was extended in 1946, when Forces 13 to 17 were added.
However, Forces 13 to 17 were intended to apply only to special cases, such
as tropical cyclones. Nowadays, the extended scale is only used in Taiwan
and mainland China, which are often affected by typhoons.
Wind speed on the 1946 Beaufort scale is based on the empirical formula:
v = 0.836 B3/2 m/s
where v is the equivalent wind speed at 10 metres above the sea surface and
B is Beaufort scale number. For example, B = 9.5 is related to 24.5 m/s
which is equal to the lower limit of "10 Beaufort". Using this formula the
highest winds in hurricanes would be 23 in the scale.
Today, hurricane force winds are sometimes described as Beaufort scale 12
through 16, very roughly related to the respective category speeds of the
Saffir-Simpson Hurricane Scale, by which actual hurricanes are measured,
where Category 1 is equivalent to Beaufort 12. However, the extended
Beaufort numbers above 13 do not match the Saffir-Simpson Scale. Category 1
tornadoes on the Fujita and TORRO scales also begin roughly at the end of
level 12 of the Beaufort scale but are indeed independent scales.
Note that wave heights in the scale are for conditions in the open ocean,
not along the shore.
Some other terms you may run across:
CI -- Current Intensity
MWS -- Mean Wind Speed
MSLP -- Mean Sea Level Atmospheric Pressure in Millibars
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