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GREATEST STORMS ON EARTH - Best Of Tornado Alley

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What causes thunder and lightning? | Thunderstorm | Video for Kids

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Aurora borealis lights up skies over Lapland

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WHAT IS THE DIFFERENCE BETWEEN CLIMATE AND WEATHER?🤷‍♂️

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WHAT IS THE DIFFERENCE BETWEEN CLIMATE AND WEATHER?🤷‍♂️

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Kid's learn about the science of climate. How it differs from weather over a long period of time.

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June 9, 2011-The March 11 earthquake and tsunami left more than 28,000 dead or missing. See incredible footage of the tsunami swamping cities and turning buildings into rubble.

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EYE WITNESS ACCOUNTS OF THE WORLD'S TALLEST TSUNAMI🌊

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EYE WITNESS ACCOUNTS OF THE WORLD'S TALLEST TSUNAMI🌊

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Home " Records " Tallest Tsunami

A tsunami with a record run-up height of 1720 feet occurred in Lituya Bay, Alaska

On the night of July 9, 1958, an earthquake along the Fairweather Fault in the Alaska Panhandle loosened about 40 million cubic yards (30.6 million cubic meters) of rock high above the northeastern shore of Lituya Bay. This mass of rock plunged from an altitude of approximately 3000 feet (914 meters) down into the waters of Gilbert Inlet (see map below). The impact force of the rockfall generated a local tsunami that crashed against the southwest shoreline of Gilbert Inlet.

The wave hit with such power that it swept completely over the spur of land that separates Gilbert Inlet from the main body of Lituya Bay. The wave then continued down the entire length of Lituya Bay, over La Chaussee Spit and into the Gulf of Alaska. The force of the wave removed all trees and vegetation from elevations as high as 1720 feet (524 meters) above sea level. Millions of trees were uprooted and swept away by the wave. This is the highest wave that has ever been known.

Detail Map: Lituya Bay, Alaska

Eyewitness Accounts from Survivors

(As reported by Don J. Miller in United States Geological Survey Professional Paper 354-C, Giant Waves in Lituya Bay, Alaska, 1960)

Mr. Ulrich and his 7-year-old son, on the Edrie, entered Lituya Bay about 8:00 p.m. and anchored in about 5 fathoms of water in a small cove on the south shore. Ulrich was awakened by the violent rocking of the boat, noted the time, and went on deck to watch the effects of the earthquake-described as violent shaking and heaving, followed by avalanching in the mountains at the head of the bay. An estimated 2 1/2 minutes after the earthquake was first felt a deafening crash was heard at the head of the bay. According to Ulrich,
"The wave definitely started in Gilbert Inlet, just before the end of the quake. It was not a wave at first. It was like an explosion, or a glacier sluff. The wave came out of the lower part, and looked like the smallest part of the whole thing. The wave did not go up 1,800 feet, the water splashed there."
Ulrich continued to watch the progress of the wave until it reached his boat about 2 1/2 to 3 minutes after it was first sighted. Being unable to get the anchor loose, he let out all of the chain (about 40 fathoms) and started the engine. Midway between the head of the bay and Cenotaph Island the wave appeared to be a straight wall of water possibly 100 feet high, extending from shore to shore. The wave was breaking as it came around the north side of the island, but on the south side it had a smooth, even crest. As it approached the Edrie the wave front appeared very steep, and 50 to 75 feet high. No lowering or other disturbance of the water around the boat, other than vibration due to the earthquake, was noticed before the wave arrived. The anchor chain snapped as the boat rose with the wave. The boat was carried toward and probably over the south shore, and then, in the backwash, toward the center of the bay. The wave crest seemed to be only 25 to 50 feet wide, and the back slope less steep than the front.

After the giant wave passed the water surface returned to about normal level, but was very turbulent, with much sloshing back and forth from shore to shore and with steep, sharp waves up to 20 feet high. These waves, however, did not show any definite movement either toward the head or the mouth of the bay. After 25 to 30 minutes the bay became calm, although floating logs covered the water near the shores and were moving out toward the center and the entrance. After the first giant wave passed Ulrich managed to keep the boat under control, and went out the entrance at 11:00 p.m. on what seemed to be a normal ebb flow.

Mr. and Mrs. Swanson on the Badger entered Lituya Bay about 9:00 p.m., first going in as far as Cenotaph Island and then returning to Anchorage Cove on the north shore near the entrance, to anchor in about 4 fathoms of water. Mr. Swanson was wakened by violent vibration of the boat, and noted the time on the clock in the pilot house. A little more than a minute after the shaking was first felt, but probably before the end of the earthquake, Swanson looked toward the head of the bay, past the north end of Cenotaph Island and saw what he thought to be the Lituya Glacier, which had "risen in the air and moved forward so it was in sight. * * * It seemed to be solid, but was jumping and shaking * * * Big cakes of ice were falling off the face of it and down into the water." After a little while "the glacier dropped back out of sight and there was a big wall of water going over the point" (the spur southwest of Gilbert Inlet). Swanson next noticed the wave climb up on the south shore near Mudslide Creek. As the wave passed Cenotaph Island it seemed to be about 50 feet high near the center of the bay and to slope up toward the sides. It passed the island about 2 1/2 minutes after it was first sighted, and reached the Badger about 1 1/2 minutes later. No lowering or other disturbance of the water around the boat was noticed before the wave arrived.

The Badger, still at anchor, was lifted up by the wave and carried across La Chaussee Spit, riding stern first just below the crest of the wave, like a surfboard. Swanson looked down on the trees growing on the spit, and believes that he was about 2 boat lengths (more than 80 feet) above their tops. The wave crest broke just outside the spit and the boat hit bottom and foundered some distance from the shore. Looking back 3 to 4 minutes after the boat hit bottom Swanson saw water pouring over the spit, carrying logs and other debris. He does not know whether this was a continuation of the wave that carried the boat over the spit or a second wave. Mr. and Mrs. Swanson abandoned their boat in a small skiff, and were picked up by another fishing boat about 2 hours later.

Landsat Image: Lituya Bay, Alaska

Conclusions

A third boat was in Lituya Bay at the time of the tsunami. It was anchored near the mouth of the bay and was sunk by the big wave. There are no known survivors from this boat, and it was believed that there were two people on board.

Prior to the July, 1958 tsunami, Don J. Miller of the United States Geological Survey had been studying evidence for the occurrence of large waves in Lituya Bay. He had documented evidence for at least four previous large waves with estimated dates of 1936, 1899, 1874, and 1853 (or 1854). All of these waves were significant in size, but shoreline evidence for all of them was removed by the 1958 wave. Mr. Miller was in Alaska when the July 1958 wave occurred and flew to Lituya Bay the following day. He took the photographs shown above in July and August and documented the older waves in United States Geological Survey Professional Paper 354-C, Giant Waves in Lituya Bay, Alaska, 1960.

With such a history of large waves, Lituya Bay should be considered as a dangerous body of water prone to a few large waves every century. When will the next one occur?

Find Other Topics on Geology.com:

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World's Biggest Tsunami | 1720 feet tall - Lituya Bay, Alaska

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The tallest wave ever recorded was a local tsunami, triggered by an earthquake and rockfall, in Lituya Bay, Alaska on July 9, 1958. The wave crashed against the opposite shoreline and ran upslope to an elevation of 1720 feet, removing trees and vegetation the entire way.

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In 1992, Bord na Móna commissioned Ireland's first commercial wind farm in Bellacorick, Co. Mayo. Over the years, we have committed to investing in the development of wind farms, contributing to Ireland meeting its 2020 renewable energy target, while also helping Ireland to build its security of energy supply. Bord na Móna has involvement with five commissioned wind farms that are supplying energy to the national grid.

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In 1992, Bord na Móna commissioned Ireland's first commercial wind farm in Bellacorick, Co. Mayo. Over the years, we have committed to investing in the development of wind farms, contributing to Ireland meeting its 2020 renewable energy target, while also helping Ireland to build its security of energy supply.

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A barometer is an instrument used to measure air pressure. The barometer measures air pressure in various kinds of units including hectopascals (hPa).

There are various types of barometers such as the water barometer, aneroid barometer, and the mercury barometer. The mercury barometer, the earliest barometer, was created by an Italian mathematician named Evangelista Torricelli in 1643.

They are used for measuring altitude, or height above the ground, such as the height of a mountain, and they were often used to measure altitude aboard a hot air balloon. Barometers are also used in modern aviation. Miners sometimes use them to determine the depth of a mine. The most used purpose of the barometer was measuring air pressure. This helps meteorologists in predicting weather.

Although Evangelista Torricelli is universally credited with inventing the barometer in 1643, historical documentation also suggests Gasparo Berti, an Italian mathematician and astronomer, unintentionally built a water barometer sometime between 1640 and 1643. French scientist and philosopher René Descartes described the design of an experiment to determine atmospheric pressure as early as 1631, but there is no evidence that he built a working barometer at that time.

Water-based barometers

The concept that decreasing atmospheric pressure predicts stormy weather, postulated by Lucien Vidi, provides the theoretical basis for a weather prediction device called a "weather glass" or a "Goethe barometer" (named for Johann Wolfgang Von Goethe, the renowned German writer and polymath who developed a simple but effective weather ball barometer using the principles developed by Torricelli). The French name, le baromètre Liègeois, is used by some English speakers. This name reflects the origins of many early weather glasses - the glass blowers of Liège, Belgium.

The weather ball barometer consists of a glass container with a sealed body, half filled with water. A narrow spout connects to the body below the water level and rises above the water level. The narrow spout is open to the atmosphere. When the air pressure is lower than it was at the time the body was sealed, the water level in the spout will rise above the water level in the body; when the air pressure is higher, the water level in the spout will drop below the water level in the body. A variation of this type of barometer can be easily made at home.

Mercury barometers

A mercury barometer has a glass tube closed at one end with an open mercury-filled reservoir at the base. The weight of the mercury creates a vacuum in the top of the tube known as Torricellian vacuum. Mercury in the tube adjusts until the weight of the mercury column balances the atmospheric force exerted on the reservoir. High atmospheric pressure places more force on the reservoir, forcing mercury higher in the column. Low pressure allows the mercury to drop to a lower level in the column by lowering the force placed on the reservoir. Since higher temperature levels around the instrument will reduce the density of the mercury, the scale for reading the height of the mercury is adjusted to compensate for this effect. The tube has to be at least as long as the amount dipping in the mercury + head space + the maximum length of the column.

Torricelli documented that the height of the mercury in a barometer changed slightly each day and concluded that this was due to the changing pressure in the atmosphere. He wrote: "We live submerged at the bottom of an ocean of elementary air, which is known by incontestable experiments to have weight".

Design changes to make the instrument more sensitive, simpler to read, and easier to transport resulted in variations such as the basin, siphon, wheel, cistern, Fortin, multiple folded, stereometric, and balance barometers. Fitzroy barometers combine the standard mercury barometer with a thermometer, as well as a guide of how to interpret pressure changes.

On June 5, 2007, a European Union directive was enacted to restrict the sale of mercury, thus effectively ending the production of new mercury barometers in Europe.

Vacuum pump oil barometer

Using vacuum pump oil as the working fluid in a barometer has led to the creation of the new "World's Tallest Barometer" in February 2013. The barometer at Portland State University (PSU) uses doubly distilled vacuum pump oil and has a nominal height of about 12.4 m for the oil column height; expected excursions are in the range of ±0.4 m over the course of a year. Vacuum pump oil has very low vapor pressure and it is available in a range of densities; the lowest density vacuum oil was chosen for the PSU barometer to maximize the oil column height.

Aneroid barometers

An aneroid barometer is an instrument for measuring pressure as a method that does not involve liquid. Invented in 1844 by French scientist Lucien Vidi, the aneroid barometer uses a small, flexible metal box called an aneroid cell (capsule), which is made from an alloy of beryllium and copper. The evacuated capsule (or usually several capsules, stacked to add up their movements) is prevented from collapsing by a strong spring. Small changes in external air pressure cause the cell to expand or contract. This expansion and contraction drives mechanical levers such that the tiny movements of the capsule are amplified and displayed on the face of the aneroid barometer. Many models include a manually set needle which is used to mark the current measurement so a change can be seen. In addition, the mechanism is made deliberately "stiff" so that tapping the barometer reveals whether the pressure is rising or falling as the pointer moves. This type of barometer is common in homes and in recreational boats, as well as small aircraft. It is also used in meteorology, mostly in barographs and as a pressure instrument in radiosondes.

Barographs

A barograph records a graph of atmospheric pressure.

MEMS Barometers

Microelectromechanical systems (or MEMS) barometers are extremely small devices between 1 and 100 micrometres in size (i.e. 0.001 to 0.1 mm). They are created via photolithography or photochemical machining. Typical applications include miniaturized weather stations, electronic barometers and altimeters.

More unusual barometers

There are many other more unusual types of barometer. From variations on the storm barometer, such as the Collins Patent Table Barometer, to more traditional-looking designs such as Hooke's Otheometer and the Ross Sympiesometer. Some, such as the Shark Oil barometer, work only in a certain temperature range, achieved in warmer climates.

The Timex Expedition WS4 features a barometric chart which is used by the watch for short-term weather forecasting. A barometer can also be found in smartphones such as the Samsung Galaxy Nexus, Samsung Galaxy S3-S6, Motorola Xoom and Apple iPhone 6 smartphones, based on MEMS and piezoresistive pressure-sensing technologies. Inclusion of barometers on smartphones was originally intended to provide a faster GPS lock. However, third party researchers were unable to confirm additional GPS accuracy or lock speed due to barometric readings. The researchers suggest that the inclusion of barometers in smartphones may provide a solution to determining a user's elevation, but also suggest that several pitfalls must first be overcome.

Applications

Barometric pressure and the pressure tendency (the change of pressure over time) have been used in weather forecasting since the late 19th century. When used in combination with wind observations, reasonably accurate short-term forecasts can be made. Simultaneous barometric readings from across a network of weather stations allow maps of air pressure to be produced, which were the first form of the modern weather map when created in the 19th century. Isobars, lines of equal pressure, when drawn on such a map, give a contour map showing areas of high and low pressure. Localized high atmospheric pressure acts as a barrier to approaching weather systems, diverting their course. Atmospheric lift caused by low-level wind convergence into the surface brings clouds and sometimes precipitation. The larger the change in pressure, especially if more than 3.5 hPa (0.1 inHg), the greater the change in weather that can be expected. If the pressure drop is rapid, a low pressure system is approaching, and there is a greater chance of rain. Rapid pressure rises, such as in the wake of a cold front, are associated with improving weather conditions, such as clearing skies.

With falling air pressure, gases trapped within the coal in deep mines can escape more freely. Thus low pressure increases the risk of firedamp accumulating. Collieries therefore keep track of the pressure. In the case of the Trimdon Grange colliery disaster of 1882 the mines inspector drew attention to the records and in the report stated "the conditions of atmosphere and temperature may be taken to have reached a dangerous point".

Aneroid barometers are used in scuba diving. A submersible pressure gauge is used to keep track of the contents of the diver's air tank. Another gauge is used to measure the hydrostatic pressure, usually expressed as a depth of sea water. Either or both gauges may be replaced with electronic variants or a dive computer.

Compensations

Temperature

The density of mercury will change with temperature, so a reading must be adjusted for the temperature of the instrument. For this purpose a mercury thermometer is usually mounted on the instrument. Temperature compensation of an aneroid barometer is accomplished by including a bi-metal element in the mechanical linkages. Aneroid barometers sold for domestic use typically have no compensation under the assumption that they will be used within a controlled room temperature range.

As the air pressure decreases at altitudes above sea level (and increases below sea level) the uncorrected reading of the barometer will depend on its location. The reading is then adjusted to an equivalent sea-level pressure for purposes of reporting. For example, if a barometer located at sea level and under fair weather conditions is moved to an altitude of 1,000 feet (305 m), about 1 inch of mercury (~35 hPa) must be added on to the reading. The barometer readings at the two locations should be the same if there are negligible changes in time, horizontal distance, and temperature. If this were not done, there would be a false indication of an approaching storm at the higher elevation.

Aneroid barometers have a mechanical adjustment that allows the equivalent sea level pressure to be read directly and without further adjustment if the instrument is not moved to a different altitude. Setting an aneroid barometer is similar to resetting an analog clock that is not at the correct time. Its dial is rotated so that the current atmospheric pressure from a known accurate and nearby barometer (such as the local weather station) is displayed. No calculation is needed, as the source barometer reading has already been converted to equivalent sea-level pressure, and this is transferred to the barometer being set-regardless of its altitude. Though somewhat rare, a few aneroid barometers intended for monitoring the weather are calibrated to manually adjust for altitude. In this case, knowing either the altitude or the current atmospheric pressure would be sufficient for future accurate readings.

Images for kids

Table of Pneumaticks, 1728 Cyclopaedia

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A barometer is an instrument used to measure air pressure. The barometer measures air pressure in various kinds of units including hectopascals (hPa). There are various types of barometers such as the water barometer, aneroid barometer, and the mercury barometer. The mercury barometer, the earliest barometer, was created by an Italian mathematician named Evangelista Torricelli in 1643.

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Dr Karl explores the magic of a rainbow

We love a good rainbow. But did you know that not all look the same? Some can be brilliantly bright and colourful and some can appear faint or dull. So when can you see the best ones?

The clearest appear when the sun is shining brightly behind you. Dark storm clouds behind them also help - the dark backdrop will allow the contrast of the colours to stand out more clearly.

WHY DO THEY APPEAR?

They appear because, thanks to the storm clouds, there are trillions of tiny raindrops floating in the air. White light from the sun enters each raindrop, refracting off the inside of the raindrop and back into your eye. The water splits the white light into all the colours of the rainbow, just like through a triangular glass prism that you might have seen in a science light experiment!

This sounds very simple, but it took thousands of years to work it out. Even geniuses like Aristotle (in Greece 2,300 years ago) and Ibn al-Haytham (in Persia 1,000 years ago) couldn't understand it! A Chinese scholar, Shen Kuo, finally figured it out - about 1,000 years ago.

If you're lucky, you might see a 'double rainbow' - a second arching above the first! Take a close look and you'll see the colours are reversed on the outer one - red will appear on the inside rather than the outside. Awesome!

DID YOU KNOW? Your shadow will always be aimed directly at the middle of a rainbow.

DID YOU KNOW? Everybody views them differently. The person right next to you is seeing it from a set of water droplets that are different from the water droplets that are creating the rainbow you see!

DID YOU KNOW? The word 'spectrum' can be used to describe the colours of the rainbow.

DID YOU KNOW? You see a semicircular rainbow only because the ground is in the way! Look out of the window next time you're in a plane - you might see a full circular one around the shadow of your plane on the clouds!

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rainbow loving and how to see the brightest with dr karl | national geographic kids

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Dr Karl explores the magic of a rainbow We love a good rainbow. But did you know that not all look the same? Some can be brilliantly bright and colourful and some can appear faint or dull. So when can you see the best ones?