Beautiful Morning
Good Morning Augusta.
This morning it is partly cloudy with a chance of a thunderstorm and a
chance of rain. High of 77F. Winds from the NW at 5 to 10 mph. Chance of
rain 30%.
Tonight it will be partly cloudy with a chance of rain. Low of 55F. Winds
less than 5 mph. Chance of rain 20%.
The readings outside at this moment taken from my own instruments are:
a relative humidity of 68.3% with a Dew Point of 62.3º F.
The temperature is 73.4ºF.
Presently we have West Northwest winds between 2.7 mph and 4.0 mph.
Our Barometric pressure is 29.77/HPA 1008.1 and rising with a weather
graphic indicating sun.
UV is 1 out of 16, sunset will be at 8:26 PM with Moon Rise at 7:24 p.m.
Eastern Daylight Time, and the moon phase is waxing gibbous.
We had 0.17 inches of rain in the past 24 hours, but no precipitation
overnight.
Visibility is 10.0 miles / 16.1 kilometers with scattered clouds to 1,0000
ft / 3048 m.
Lightening is dangerous and here is why.
The term lightning flash is used to describe the entire discharge, which
takes on the order of 0.2 seconds. But a flash is usually made up of several
shorter discharges which last less than a millisecond and which repeat
rapidly enough that the eye cannot resolve the multiple events. These
individual discharges are called strokes. Sometimes the strokes are
separated enough in time for the eye to resolve them, and the lightning
appears to flicker.
When it comes to voltage, Williams says a typical lightning bolt bridges a
potential difference (voltage) of several hundred million volts.
He also says that a typical lightning bolt may transfer 1020 electrons in a
fraction of a second, developing a peak current of up to 10 kiloamperes.
According to Uman, the German scientist Pockels discovered that basalt rock
in the vicinity of lightning strikes was magnetized and deduced currents on
the order of 10,000 amps in 1897. (To put that in perspective for you, a
common electric circuit in your home is 15 amps, and an appliance circuit in
your kitchen, such as for your regrigerator, is 20 amps. Your electric stove
typicaly draws 50 amps, and your clothes dryer will draw 30)
Ampere's law allows you to deduce the current in a wire from the measurement
of the magnetic field at some radius from the wire. Pockels presumably had
measured the magnetizing effects of large currents on basalt and was able to
scale those experiments to estimate the current associated with the
lightning. Based on that principle, magnetic links are widely used for the
measurement of the lightning currents. Most measurements have been in the
range 5,000 to 20,000 amps but a famous strike just before the Apollo 15
launch in 1971 was measured at 100,000 amperes by magnetic links attached to
the umbilical tower. Currents over 200,000 amps have been reported.
One could envision a magnetic detector based on both Ampere's law and
Faraday's law which could give you an estimate of lightning current provided
you had a measurement of the distance from the detector to the lightning
strike point. If you set up a coil of wire in a vertical plane, then the
rate of change of magnetic field through the coil would generate a voltage.
If you could sum (integrate) the current generated by that voltage, you
could calculate the charge transferred in the lightning strike. With several
such detectors in an area, you could model the location as well as the
charge associated with the strike.
Most commonly, the lightning current ceases in about a millisecond for a
given stroke, but sometimes there is a continuing current on the order of
100 amps following one or more of the strokes. This is called "hot
lightning" and it is the cause of lightning fires according to Uman. The
temperatures of lightning are 15,000-60,000°F for both "cold" and "hot"
lightning - it is the continuing current that starts some 10,000 fires per
year in the U.S. in the estimation of Uman.
Threat to human life in storms -The following data is from an Atlanta
Journal article
About 95 people die from lightning yearly in the U.S.
A single thunderstorm can release 125 million gallons of water (that's the
volume of 16 Washington Monuments).
One storm can discharge enough energy to supply the entire U.S. with
electricity for 20 minutes
A large Midwestern cumulonimbus can tower 12-15 miles (Mount Everest is 5.5
miles high.)
There are approximately 2,000 thunderstorms at any given moment worldwide.
Lightning has killed 6,000 persons in the United States in the past 34
years. In 1990, 74 persons were killed and 252 more were injured. Florida is
the most dangerous state with 14 killed and 27 injured in 1990. In 1987 an
Atlas-Centaur rocket was struck by lightning on launch and had to be
destroyed.
This morning it is partly cloudy with a chance of a thunderstorm and a
chance of rain. High of 77F. Winds from the NW at 5 to 10 mph. Chance of
rain 30%.
Tonight it will be partly cloudy with a chance of rain. Low of 55F. Winds
less than 5 mph. Chance of rain 20%.
The readings outside at this moment taken from my own instruments are:
a relative humidity of 68.3% with a Dew Point of 62.3º F.
The temperature is 73.4ºF.
Presently we have West Northwest winds between 2.7 mph and 4.0 mph.
Our Barometric pressure is 29.77/HPA 1008.1 and rising with a weather
graphic indicating sun.
UV is 1 out of 16, sunset will be at 8:26 PM with Moon Rise at 7:24 p.m.
Eastern Daylight Time, and the moon phase is waxing gibbous.
We had 0.17 inches of rain in the past 24 hours, but no precipitation
overnight.
Visibility is 10.0 miles / 16.1 kilometers with scattered clouds to 1,0000
ft / 3048 m.
Lightening is dangerous and here is why.
The term lightning flash is used to describe the entire discharge, which
takes on the order of 0.2 seconds. But a flash is usually made up of several
shorter discharges which last less than a millisecond and which repeat
rapidly enough that the eye cannot resolve the multiple events. These
individual discharges are called strokes. Sometimes the strokes are
separated enough in time for the eye to resolve them, and the lightning
appears to flicker.
When it comes to voltage, Williams says a typical lightning bolt bridges a
potential difference (voltage) of several hundred million volts.
He also says that a typical lightning bolt may transfer 1020 electrons in a
fraction of a second, developing a peak current of up to 10 kiloamperes.
According to Uman, the German scientist Pockels discovered that basalt rock
in the vicinity of lightning strikes was magnetized and deduced currents on
the order of 10,000 amps in 1897. (To put that in perspective for you, a
common electric circuit in your home is 15 amps, and an appliance circuit in
your kitchen, such as for your regrigerator, is 20 amps. Your electric stove
typicaly draws 50 amps, and your clothes dryer will draw 30)
Ampere's law allows you to deduce the current in a wire from the measurement
of the magnetic field at some radius from the wire. Pockels presumably had
measured the magnetizing effects of large currents on basalt and was able to
scale those experiments to estimate the current associated with the
lightning. Based on that principle, magnetic links are widely used for the
measurement of the lightning currents. Most measurements have been in the
range 5,000 to 20,000 amps but a famous strike just before the Apollo 15
launch in 1971 was measured at 100,000 amperes by magnetic links attached to
the umbilical tower. Currents over 200,000 amps have been reported.
One could envision a magnetic detector based on both Ampere's law and
Faraday's law which could give you an estimate of lightning current provided
you had a measurement of the distance from the detector to the lightning
strike point. If you set up a coil of wire in a vertical plane, then the
rate of change of magnetic field through the coil would generate a voltage.
If you could sum (integrate) the current generated by that voltage, you
could calculate the charge transferred in the lightning strike. With several
such detectors in an area, you could model the location as well as the
charge associated with the strike.
Most commonly, the lightning current ceases in about a millisecond for a
given stroke, but sometimes there is a continuing current on the order of
100 amps following one or more of the strokes. This is called "hot
lightning" and it is the cause of lightning fires according to Uman. The
temperatures of lightning are 15,000-60,000°F for both "cold" and "hot"
lightning - it is the continuing current that starts some 10,000 fires per
year in the U.S. in the estimation of Uman.
Threat to human life in storms -The following data is from an Atlanta
Journal article
About 95 people die from lightning yearly in the U.S.
A single thunderstorm can release 125 million gallons of water (that's the
volume of 16 Washington Monuments).
One storm can discharge enough energy to supply the entire U.S. with
electricity for 20 minutes
A large Midwestern cumulonimbus can tower 12-15 miles (Mount Everest is 5.5
miles high.)
There are approximately 2,000 thunderstorms at any given moment worldwide.
Lightning has killed 6,000 persons in the United States in the past 34
years. In 1990, 74 persons were killed and 252 more were injured. Florida is
the most dangerous state with 14 killed and 27 injured in 1990. In 1987 an
Atlas-Centaur rocket was struck by lightning on launch and had to be
destroyed.
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