More than fifty dead as Hurricane Ida batters the American east coast.

More than fifty people have now died in the US in incidents linked to Hurricane Ida, which made landfall in Louisiana on Sunday 29 August 2021. The majority of the deaths occurred in northeastern states, which historically have not suffered many such events and were poorly prepared, with the highest number of deaths was recorded in New Jersey, where at least 23 people have died, mostly of drowning after becoming trapped in cars or flooded apartments, although the state was hit by at least one tornado generated by the hurricane, which is reported to have destroyed its largest dairy farm. 

 

Flooding in Manville, New Jersey, on Thursday 2 September 2021. Andrew Mills/NJ Advance Media.

At least fourteen people, including a two year old boy, have lost their lives in New York City, with eleven victims confirmed to have drowned after becoming trapped in flooded basements. The city was forced to temporarily close its streets to non-emergency vehicles to enable rescue work to be carried out, the subway network was closed due to flooding, and thousands of homes were left without power. 80 mm of rain fell in an hour in Central Park, surpassing a previous record of 49 mm, set only a month ago by another tropical storm that hit the city.

 

Flooding in New York linked to Hurricane Ida. AP.

Nine people are reported to have died in storm-related events in Louisiana, including at least one person who drowned, and three who died of carbon monoxide poisoning. However, the fact that the death toll was not much higher has been hailed as a vindication of the billions of dollars that have been invested in the leve system protecting the city of New Orleans following the catastrophic damage caused by Hurricane Katrina sixteen years ago. The city, which was directly in the path of the storm, suffered wind damage as it was battered by 240 km per hour winds, but only a limited amount of flooding. A plan to evacuate large parts of New Orleans in the event of it being hit by another major hurricane was not put into place because of the rapidity with which the storm formed, developing over the Caribbean Sea only four days before making landfall as the fifth largest storm ever to hit the US coast.

 

Buildings demolished by high winds as Hurricane Ida swept over New Orleans. Brandon Bell/Getty Images.

Elsewhere, at least five people have died in Pennsylvania, two each in Mississippi and Alabama, and one death each in Connecticut, Maryland, and Virginia. Many officials in the US, including President Joe Biden, have linked the storm directly to global warming, noting that the average storm hitting the US today does seven times as much damage as in the 1970s, that 'hundred year' storms now happen several times a decade, and that states formerly to the north of the hurricane zone are now regularly hit by these storms.

 

Floodwaters in Bridgeville, Pennsylvania, associated with Hurricane Ida. Pittsburgh Post Gazette/AP.

Tropical storms, known as hurricanes in the Atlantic and eastern Pacific, are caused by solar energy heating the air above the oceans, which causes the air to rise leading to an inrush of air. If this happens over a large enough area the inrushing air will start to circulate, as the rotation of the Earth causes the winds closer to the equator to move eastwards compared to those further away (the Coriolis Effect). This leads to tropical storms rotating clockwise in the southern hemisphere and anticlockwise in the northern hemisphere. These storms tend to grow in strength as they move across the ocean and lose it as they pass over land (this is not completely true: many tropical storms peter out without reaching land due to wider atmospheric patterns), since the land tends to absorb solar energy while the sea reflects it.

 

The formation of a tropical cyclone. Natural Disaster Management.

Despite the obvious danger of winds of this speed, which can physically blow people, and other large objects, away as well as damaging buildings and uprooting trees, the real danger from these storms comes from the flooding they bring. Each drop millibar drop in air-pressure leads to an approximate 1 cm rise in sea level, with big tropical storms capable of causing a storm surge of several meters. This is always accompanied by heavy rainfall, since warm air over the ocean leads to evaporation of sea water, which is then carried with the storm. These combined often lead to catastrophic flooding in areas hit by tropical storms.

 

The formation and impact of a storm surge. eSchoolToday.

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Tropical Storm Isias kills at least twelve in Puerto Rico, the Dominican Republic, the Bahamas, and the United States.

Tropical Storm Isias has killed at least twelve people as it swept across the Caribbean and the Eastern Seaboard of the United States. The storm reached hurricane strength in the Caribbean, sweeping to the south of Puerto Rico, where it caused high winds and flooding, and led to three known deaths. Chiche Peguero, 53, of Río San Juan in María Trinidad Sánchez Province, who was electrocuted by a falling power line, a woman drowned after being swept into a river in Rincón Province, and a five-year-old boy who was killed by a falling tree at Altamira in Puerto Plata Province. Across the island about 448 000 people were left without electricity, and many roads were flooded. severley hampering travel and communication. The storm swept across the Dominican Republic, causing widespread flooding, and causing the death of a horse and its rider who were again hit by a falling power line. The storm reached the Bahamas on 31 July 2020, causing widespread flooding and wind-damage, before moving towards the coast of the United States.

Workers clearing debris left by Hurricane Isias in the Dominican Republic. Erika Santelices/AFP.

The passed to the east of Florida on 1 August 2020, causing some flooding and power outages, but few serious problems, however as it made landfall in North Carolina it caused more severe flooding, and triggered a series of tornadoes, one of which struck a trailer park in Bertie County, killing at least two people, with around twenty injured and three more still missing. From here it passed northward through Virginia, Maryland and Delaware, causing widespread flooding, wind damage and power-outages, with one person killed in Milford, Delaware, when her vehicle was struck by a falling tree. The storm caused further flooding in Pennsylvania, where it claimed another life as a 44-year-old woman and her car were swept away by floodwaters in Lehigh County.

Damage to boats at Southport Marina in Brunswick County, North Carolina, following the passage of Hurricane Isias. Ken Blevins/Star News.

Further north the storm caused flooding and tornadoes in New Jersey, causing damage to a number of homes and businesses, and the collapse of a church steeple in Ocean City. A 21-year-old man drowned off the coast of Cape May in New Jersey, another person was killed when a falling tree hit their car in Queens, New York, and a third death was also caused by a falling tree in New Haven County, Connecticut.

Damage to hourses in Cape May County, New Jersey, caused by Tropical Storm Isias. NCB10.

Tropical storms are caused by solar energy heating the air above the oceans, which causes the air to rise leading to an inrush of air. If this happens over a large enough area the inrushing air will start to circulate, as the rotation of the Earth causes the winds closer to the equator to move eastwards compared to those further away (the Coriolis Effect). This leads to tropical storms rotating clockwise in the southern hemisphere and anticlockwise in the northern hemisphere. These storms tend to grow in strength as they move across the ocean and lose it as they pass over land (this is not completely true: many tropical storms peter out without reaching land due to wider atmospheric patterns), since the land tends to absorb solar energy while the sea reflects it.

The path and strength of Tropical Storm Isias. Thick line indicates the past path of the storm (till 9.00 am GMT on Wednesday 5 August 2020), while the thin line indicates the predicted future path of the storm, and the dotted circles the margin of error at nine and twenty one, hours ahead. Colour indicated the severity of the storm. Tropical Storm Risk.

Despite the obvious danger of winds of this speed, which can physically blow people, and other large objects, away as well as damaging buildings and uprooting trees, the real danger from these storms comes from the flooding they bring. Each drop millibar drop in air-pressure leads to an approximate 1 cm rise in sea level, with big tropical storms capable of causing a storm surge of several meters. This is always accompanied by heavy rainfall, since warm air over the ocean leads to evaporation of sea water, which is then carried with the storm. These combined often lead to catastrophic flooding in areas hit by tropical storms.

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Bright fireball meteor off the east coast of North America.

The American Meteor Society has received reports of a bright fireball meteor being seen off the east coast of the United States at about 6.35 am Eastern Standard Time (11.35 am GMT) on Wednesday 9 January 2019. The meteor was seen from Delaware, Maryland, New Jersey, North Carolina, New York, Pennsylvania, and Virginia. A fireball is defined as a meteor (shooting star) brighter than the planet Venus. These are typically caused by pieces of rock burning up in the atmosphere, but can be the result of man-made space-junk burning up on re-entry. This object appeared to move northeast-to-southwest.

The 9 January 2019 American East Coast Meteor, seen from West New York in New Jersey. Jeremy Settle/News 12 New Jersey/American Meteor Society.

Objects of this size probably enter the Earth's atmosphere several times a year, though unless they do so over populated areas they are unlikely to be noticed. They are officially described as fireballs if they produce a light brighter than the planet Venus. The brightness of a meteor is caused by friction with the Earth's atmosphere, which is typically far greater than that caused by simple falling, due to the initial trajectory of the object. Such objects typically eventually explode in an airburst called by the friction, causing them to vanish as an luminous object. However this is not the end of the story as such explosions result in the production of a number of smaller objects, which fall to the ground under the influence of gravity (which does not cause the luminescence associated with friction-induced heating).

 

Map showing areas where sightings of the meteor were reported, and the route of the object (blue arrow). American Meteor Society.

 

These 'dark objects' do not continue along the path of the original bolide, but neither do they fall directly to the ground, but rather follow a course determined by the atmospheric currents (winds) through which the objects pass. Scientists are able to calculate potential trajectories for hypothetical dark objects derived from meteors using data from weather monitoring services.

Witness reports can help astronomers to understand these events. If you witness a fireball-type meteor over the US you can report it to the American Meteor Society here.   

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Evacuations as City of Lynchburg, Virginia, threatened by dam collapse.

Over a hundred homes in the City of Lynchburg, Virginia, were evacuated on the evening of Thursday2 August 2018, following concerns that the Collage Lake Dam might collapse. A total of 34 mm of rain fell in the area on Thursday and 1.65 on Wednesday, causing the already high water to begin to overtop the dam, prompting fears that the structure might fail, which it was predicted would lead to the water on the Blackwater Creek running through the city rising by as much as 5 m in under 7 minutes.

College Lake Dam on Friday 3 August 2018. Not debris on top of dam left by flooding and damage to structure left of centre of image. WSLS 10 News.

Engineers were able to lower water levels bellow the dam by releasing water through side sluices, and by 1.00 pm on Friday 3 August the structure was considered safe. Much of the Eastern Seaboard of the United States has been suffering heavy rainfall and related flooding events this week, driven by exceptionally warm temperatures over the Caribbean, which has led to water soaked air currents pushing northwards, causing problems as far north as Vermont and inland as far as the Mississippi River Valley.

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Landslide destroys home in Roanoke County, Virginia.

A family of three were forced to flee their home when it slid off its foundations and slid about six metres down a hillslope after being hit by a mudslide on Friday 18 May 2018. The family were sleeping in the home in the town of Vinton in the east of the county, when the property began to shift, at about 4.45 am local time. The family were able to escape through a hoke that opened up in a brick wall as the property moved.

The scene of a landslide in Roanoke County, Virginia, which shifted a house off its foundations and six metres downslope. Roanoke County Fire and Rescue.

The incident happened after several hours of heavy rain in the area, which appears to have destabilized exposed sediment on a construction site upslope of the home. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall.

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Meteorite stolen from Virginia museum.

A meteorite has been stolen from the Science Museum of Virginia in Richmond. The rock, which was contained in a metal stand in an exhibit on the museum's first floor was removed some time between 9.30 am and 2.30 pm on Thursday 15 March 2018, by a thief who apparently used some sort of tool to partially dismantle the stand. Virginia Capitol Police are seeking the perpetrator of the crime, however the item, a nickel-iron meteorite about the size of a tennis ball, may be hard to dispose of, as it is not particularly uncommon, giving it a low value (about US$1500) and a limited number of potential buyers. The museum expects to be able to replace the meteorite cheaply and within a few days.

A meteorite that was stolen from the Science Museum of Virginia on 15 March 2018. Virginia Capitol Police.

Nickel-iron meteorites, or octahedrites, are the most common class of meteorite, being comprised largely of iron with a substantial amount of nickel, leading to the formation of the mineral kamacite, which has an octahedral form, giving these meteorites their name. Strictly speaking iron meteorites are less common than stony meteorites, but they are much more commonly found as they are resilient both to atmospheric entry and terrestrial weathering, and relatively easy to recognise. Only about 5.7% of objects entering the atmosphere are thought to be iron meteorites, but they comprise about 90% of objects in collections. Nickel-iron meteorites are the most common form of iron meteorite, though low-nickel meteorites hexahedrites, are also found. Both are thought to have formed within the interior of large planetesimals in the early Solar System. These bodies were large enough to develop differentiated iron cores (as is seen in the Earth today), but which were subsequently torn apart by tidal forces generated by the larger planets.

Anyone with information on the crime can contact the Virginia Capitol Police on (804) 786-2120. 

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