Tropical storms quiz

Hurricane harvey: why did it flood so badly in and around houston? Should they have called for an evacuation of houston?

"Urban sprawl" Maybe rewatch harvey video Important points Because of urbanization, theres more concrete. With concrete, theres nowhere for the water to go, it cant sink into the ground, it creates rivers 500 yr floods are considered a 0.2 % chance, but there have been 3 of them in houston in the last few decades so this stat is probably wrong. We dont know all the info about floods in houston from the last 500 yrs so this is kind wrong Should houston have ben evacuated? In hurricane rita in 2005 they evacuated and there were huge traffic jams, dozens of people died in the heat and from lack of access to emergency services So its risky to call an evacuation for a storm so big. They just told people to get to a higher up area of the city. For like 7 days, 3,600 sq miles were covered in more than 40 inches of rain and then even bigger areas had 30 and 20 inches

This years hurricanes

(from 9/10) Hurricane dorian has moved up by georgia and is gaining strength over the warm waters, it is now a category 5 storm (winds of 190 mph) its caused a ton of damage in the bahamas It is dragging ocean water inland (super high tides) The center of it missed florida The most intense part of the storm (most intense winds) are just outside of the eye, the "eye wall". What maintains hurricanes is the temp of the ocean water, when its warmer the storm gets more intense because of advection (?) Water can get dragged very far inland in FL because it is so flat there There are 2 typhoons currently in japan and korea: faxai and lingling. Theyre category 1 but still very large 9+ people have died So, hurricanes are not just in the atlantic sector.

Solar heating of earth varies with latitude

(the earth is a ball) which is why all these things happen. - Equal amounts of sunlight spread over more surface area near the poles than in the tropics. Also, ice near the poles reflects much of the energy that reaches the surface there. Effect is net heat gain and surplus in tropics, net heat deficit in polar areas This imbalance is what causes circulation in the atmosphere and the ocean

Earthquakes

-55% of people killed in natural disasters are killed by earthquakes or the tsunamis the occur as a result of these -18% are from storms, 12% from extreme temps, 12% from floods -While earthquakes do not occur the most, theyre typically super destructive -Earthquakes are not very predictable

economic damage

-71% of economic damage by natural disasters was from weather related events (94-2015) -storms cost the most (38% of economic damage of all natural disasters) -geophysical occurrences came 2nd at 29%, then floods at 25%

origin of a hurricane

-Over warm water within few degrees of equator.- Initially a storm will start as a thunderhead, a localized heating area causes intitial uplift and formation of thunderstorms Once it gets big enough in scale, the mass begins to rotate because of the rotation of the earth

Free convection in the atmosphere

-Theres warm air on the ground which gets cooler as you go up in the atmosphere -Warm air is less dense so it move up in the atmosphere, and if theres water in that warm air mass, it will evaporate/rain out as it moves upward -Hot air rises bc its less dense (see pic on phone)

Gas, temperature, and pressure

-air cools when it expands, warms when it is compressed -Rising warm air tends to form droplets (clouds and rain) as it expands and cools -convection

Hurricane circulation

-evaporation from the warm oceans surface supplies the storms fuel -winds near the surface carry warm, moist air in toward the storm center -the warm humid air rises rapidly in the thunderstorm updrafts near the center -air flows outwardly from the center, in the cooler upper levels of the storm -(look at pics on phone) ------ Tons of the warm water in the ocean gets dragged up and dumped out This is the most efficient heat exchanger Hurricanes leave water behind them like 10 degrees celsius colder than it was before The highest winds and precipitation occur in the eye wall The lowest pressure is in the eye Eye can be 10-20 miles (20-30km) wide -look at slice graph pic

tropical cyclones

-one particular category of storm- biggest ones are hurricanes/typhoones which are just different names for the same things. -Theyre fed by the warm water theyre movng over (evaporation) -These are giant heat engines, fueled by the storage and release of oceanic heat by evaporation and condensation

Hurricane (tropical cyclone)

-sustained wind speeds greater than 74 mph, theres a well defined "eye", cyclonic shape -Categories of hurricanes are broken down by windspeed -The clouds/storms are completely solidly together

Tropical storm

-system of strong thunderstorms with a defined surface circulation, wind speed between 39-73 mph, has a cyclonic shape, but usually without a well defined "eye" -Very well defined rotation counterclockwise, no eye (this is the stage after tropical depression. at this point storms and clouds coalesce and start rotating to start the beginning of a hurricane)

weather related disasters

-these claimed 625,000 lives from 1994-2013 -left 4 billion people homeless, injured, or in need of emergency assistance -71% of economic damage by natural disasters was from weather related events (94-2015)

Things that help with surge

1. swamps and mangrove forests Salwater incursion can damage or destroy frshwater eco systems, but these dissipate the wave energy. Wetlands and vegetation can diminish storm surge energy greatly. Its a natural barrier 2. Reefs and wide expanses of shallower water always diminish surge enrgy 3. Barrier islands: low lying sand bars and sand dunes that build up in shallow water and protect inland Barrier island: low lying sand bars/dunes that build up in shallow water areas along coasts. People build their homes on these sometimes These acts as barriers because the storm looses energy going over it, the storm surge slows down and the waves break up a bit, also the storm isnt going over water Surges and barrier islands: Heavy storm erosion is a natural part of porvess of barrier island migration (the islands move elsewhere) Theres another bullet on the slid Barrier islands Mangrove waters are saltwaters adaptions, and these wetlands and vegetation can diminish storm surge energy greatly Reefs and wide expanses of shallow water Sand dunes and barrier islands provide a buffer zone for communities Development of the coastal region puts population in harms way and diminished the natural defenses such as dunes, wetlands, and mangrove forests High water in storm surge is mostly due to wind drag on the ocean surface. Low atmosphere pressure does pull water up, but only like 5 %.

Haiti earthquake 2010

7 on Richter scale, killed 230,000 ppl, 10 billion dollars in damage

Air mass and pressure

Air column from sea level to top of atmosphere weights about 2.3 pounds or 1 kg per centimeter squared Mass produces pressure 14.7 pounds per square inch at sea level (1 bar or 1000 millibars) -expands and cools when pressure is reduced -contracts and warms when pressure is increased

Hurricane emily

Category 5 hit jamaica in 2005 had 160 mph winds, 17 lives lost, 1 billion dollars in damage

Ferrel Cell

Cell that moves air form 30 degrees to 60 degrees latitude (see pic)

Polar Cell

Cells of air circulation occurring between 60 degrees north and south and each pole. (see pic)

Atmospheric circulation cells

Convection and coreolis effect produce zones defined by prevailing winds Where air is ascending and descending between cells, calm air prevails Equatorial doldrums or ITCZ (intertropical convergence zone Warm, humid air ascends -> heavy rainfall In between lie bands of dependable winds Trade winds (easterlies) are surface winds centered around 15 ̊ north and south latitude Westerlies are surface winds centered around 45 ̊ north and south latitude Well organized cells are idealized; reality is more complicated and changes constantly

Galveston hurricane (1900)

Deadliest natural disaster in US history. 6,000-12,000 people died as a storm surge washed without warning over the entire low lying barrier island (essentially a sand bar) on the coast of texas. Galveston now has a seawall the they constructed after the hurricance to protect people/property 10-12 ft tall, made of concrete It works, in 2008 it worked as designed But, many expensive beach homes built outside the sea wall were destroyed

Hurricane anatomy terms

Eye: center of hurricane, not wet, theres cold descending air, pressure drop Eyewall: most intense wind speeds, max wind speeds are just outside the wall Spiral rain bands: because of coreolis Barometric pressure: at surface, 1000 mb is typical and a 40 mb drop is significant and characteristic of a hurricane eye Look at naples, FL image to see what happense to pressure and wind when a hurricane passes

Hurricane prediction and planning

Great: fewer deaths from hurricanes over time due to big improvements in predicting path and strength of hurricanes and planning for evacutation, shelter, emergency response Not so great: cost impact keeps going up. Why? More storms due to global warming? Or just more stuff in harms way? Look at deadliest and costliest slides Katrina is the costliest US hurricane from 1900-2016 Less deaths tho Hurricane watches and warnings: on slide Look at last 3 slides

Surge height

Height varies with wind speed and fetch (distance wind blows over open water) As surge enters shallow water it slows and piles up Bays and inlets channel water into smaller area to increase surge height Once surge hits, it is not just water but also debris Similar to tsunamis Fetch is the uninterrupted distance over which wind blows without significant change in direction- determines size of both waves and surge Height varies with wind speed and fetch ( distance travelled over open water) Surges that coincide with high tide and are higher with greater inland reach Inland reach of storm surge depends on topography, vegetation, and natural barriers (or unnatural like levees) Low llying coasts are more vulnerable than coasts up high (like on sea cliffs) Besides flooding: surge damage includes contamination of water supplies If they hit and oil plant that would be bad, sewage. Theres a reason why theres no nucear plants in houston Houses that are poorly anchored to foundations or support piers can float Waves, especially on top of the storm surge, can erode the beach or just the general landscape and undermine structures This is why some people will get piling in bedrock, but its expensie so others dont Height varies with wind speed (sustained wind speeds, not just gusts) and fetvh (distance wind blows over open water) As surge enters shallow water it slows and piles up Bays and inlets channel water into smaller area to increase surge height Once surge hits, its not just water, theres debris wthin it

Hazards assoc. With hurricanes and typhoons

High winds (ex: irma in caribbean islanss) Intense rainfall (ex: harvey, florence, dorian)- flooding, landslides Flooding by storm surge- the water in the ocean is pushed by the strong winds into a bulge ahead of the storm

dropsondes

Hurricane hunters deploy these within the hurricane itself. Its a tube with instruments in it connected to a parachute, they throw out as many as they can Theres GPS, measures pressure, wind speed, temperature, humidity etc

Hurricane season

Hurricane season peaks around september 10th. The season goes from mid july to mid october. (for atlantic oceans, carribbean, hurricanes that form in the gulf of mexico) So dont visit FL or the caribbean island in september Oddly tho, temperatures in the northern hemisphere actually dont peak in september. They peak in mid august (july actually i think). So if hurricanes are fueled by heat, why dont they peak in august? Development factors: warm water, land interaction, wind shear. Anyways, the reason hurricanes max out in september is because thats when ocean temperatures reach their peak. (late august/early september) thats one reason why hurricane season is it when it is. They depend on seas surface temperature which is still charging in july and august. Its bc of heat capacity of water Trade winds also reach their peak i think at this point, they move warm water and warm air (maybe?)

Uncertainty in hurricane prediction

Hurricanes can quickly change path or increase in intensity Time of arrival is moderately predicatble Specific location or landfall and storm strength at landfall are poorly known more than day or two in advance NHC's current 24 hr lateral forecast errr for path of hurricane is 80 km Smaller storms can quickly gain energy to become powerful hurricanes

Hurricane basics

Hurricanes form from tropical disturbance (due to wind convergence) between 8 and 20 latitude Build in intensity over warm ocean water Dissipate over cooler water and land Move in somewhat predictable ways, steered by winds and meteorological high and low pressure zones Nearly all hurricanes initialize in the same spot, but they can travel ddifferently Hurricanes move in a counter clockwise rotation because of the coreolis effect. Zero at equator, greatest at poles

Hurricane Katrina

In 2005 this storm killed 1,800 people and cause $180 billion in damage It was fueled by the warm waters of the gulf of mexico. It hit new orleans and broke the levies New orleans is where it hit People would get trapped in their attics and drown Homes could be completely underwater, people would sit on top of their homes and wait for help

The costliest hurricane in US history

Katrina

Ingredients to make and sustain a hurricane

Low atmospheric pressure, humid air, and initially light/moderate winds to allow convective updrafts to build. Too strong of winds or wind shear will break up the updrafts (not allowing for a hurricane) Warm surface water (warmer than 79 degrees F or 26 degrees C) These conditions happen in late summer to fall which is why it is hurricane season

Forecasting and prediction

Modern weather satellites monitor potential storms while doppler radar (on the ground) tracks storms as they approach land Hurricane hunters and other aircraft collect direct and remote sensing data on winds nd atmosphere pressure And release dropsonde sensing instruments on parachutes into storm to transmit... on slide Who is making forecasts? Many organizations, both governmental and commercial (accuweather, weather channel, etc) Most importantly: national ocean and atmosphere admin. (NOAA) nat hurricane center (NHC) nat weather service (NWS) Why governmental? (why cant a provide institution prove this info) need for expensive satellites to provide data Need for an organization with responsibility and authority to porivde the official forecasts and warnings when necissary . people want to know this info is credible Spaghetti plots show the output of many different computer model situations Theyre used to test the uncertaintty in the path the storm will take When they agree, confidence is high, when they disagree, confidence is low in some or all In general, predicition is very good. Much better than 20 or 30 years ago but since storm intensity and direction can change quickly based on local details, there is still considerable uncertainty on exact time and location of landfall, as well as intensity

Hurricane cross section

See screenshot of cross section of the core of a typical hurricane Cold dry descending air in the eye, relatively stable air compared to the instability of the air in the storm There are many convective cells occuring in a hurricane They take up hundreds of miles Height of hurricanes are several miles (7-10 for irma) Most intense rainfall occurs right outside of the eye wall

Forced convection in the atmosphere

The air moves toward a low pressure center at the ground 'Squeezed' air rises bc it has nowhere else to go but up (pic on slides/phone)

Why do northern hemisphere tropical cyclones rotate counter clockwise

The coreolis effect (see pic on phone) -Things move to the right in the northern hemisphere as you move across large distances. This is why planes dont fly straight. The fastest route on a sphere is an arc -Air masses going from north to south curve right In the south it is the opposite -The poles rotate slowest and the equator has to move faster -Think rollerblading in a line of people around in a circle, the person in the middle hardly has to move, the person on the outside is flying around super fast -overall , the coreolis deflects the path of moving object from viewers perspective -to the right in northern hemisphere, and to left in southern hemisphere due to earths rotation -The coreolis effect is zero at the equator (if you are throwing a ball just across the equator nothing will happen) -The coreolis effect is greatest at the poles -Change in earths rotating velocity with latitude: 0 km/hr at poles, more than 1600 km/hr at equator (1000 mph) -Greatest effect on objects that move long distances across latitudes -If you are standing in the middle of a very fast carousel and throw a ball at someone, its probably going to hit someone right or left of that person

Hurricanes are fueled by

The key to hurricanes is that they have to be fueled by heat (wind shear also matter but not as much) Theyre fueled by the oceans heat energy and pushed along by the trade winds. The sea surface temperature is greatest near the equator. Most of the heat is at the equator and then the atm distributes it to the rest of the world But this is why most hurricanes happen in the tropics is cause of the warmth Hurricanes tend to exist right outside the equator (not on it because of a different phenomoena that exists) In the southern hemisphere, hurricanes happen in our spring, its the opposite and they also rotate opposite

severity of a disaster

The severity of a disaster is commonly measured in terms of the number of fatalities it causes or the monetary loss it causes

storm surge

This is the most destrutive componentt of a hurricane. Surges and associated flodding account for 90% of hurricane deaths. Its so quick and large It depends on the geographic location as to how much the storm surge will do irma s storm surge was not as bad as feared in florida because it took a path where the eastern side of the storm i think was pretty much on land, and since it spins counter clockwise due to coreolis, there wasnt much water to drag into the northeast quadrant. If it wouldve hit the other side of fl/ the other east coast states, the storm wouldve been much worse because pretty much the whole hurricane was over water. Eastern sea board (??) Sandy had pretty bad surge in NYC and jersey The water flooded the subway system and also the streets were flooded so noone could really get anywhere in NYC Surge is in part due to to the rise of water beneath the low pressure center, but mostly due to sustained winds piling up water in front of the storm (see pic) Most intense surge is in northeastern quadrants Surge height- In the northern hemisphere, things are turning counter clockwise, and surge is highest in forward right quadrant of the storm Storm surge is mainly from the wind, a small fraction from the low pressure itself East coast hurricanes are most dangerous when they just sit right on the coast (see pic) because the surge can just soak them And combine that with the heavy rains and its really bad You also get a small pressure surge by the wind driven surge If you have high tides combined with a storm surge thats really a problem because the water will just keep pushing further and further inland Hurrican ike in 2008 had a detrimental storm surge, but galveston was fine bc they had their sea wall The northeast quadrant gets quite a bit more damage due to surge than the southwest Hurricane ike was an example of this The water can drop right before the storm surge It gets really low and then really high

Hurricane intensity scale (saffir simpson)

This only tells how strong te winds are Category 1= 79-95 mph Category 2= 95-110 110-130 130-156 156+ This doesnt necessarily equate to destruction from rain and flooding or storm surge, it only tells us about about wind speed. Once you get to category 3, thats when things get super destructive. Most decent buildings can handle up to 100 mph winds. BUT, winds (category size) arent what really equate to damage, because flooding causes a lot of the damage A category 1 and 5 can cause the same amount of damage. But, the probability of damage goes up w category

more on uneven heating

We get more light at the equator then at the poles In the winter in the northern hemisphere we are tilted away from the sun, opposite in southern hemisphere In the spring the sun is aimed directly at the equator so theres not much of a tilt Hypothetically, due to the uneven solar heating, the warm air at the equator should move toward the poles and the cold air at the poles should drop down to the equator What makes the wind blow? Driven by pressure differences pressure differences ... which in turn are created by density differences. Air flows from high pressure to low pressure ( i.e., the wind blows!) Rising warm, humid air creates low pressure Sinking cold, dry air creates high pressure

Air

Which is denser and heavier? Warm humid air or cold dry air? Air can hold water vapor up to 4% in value Density varies, density decreases with altitude, warm air is less dense than cold air (think of a hot air balloon), humid air is less dense than dry air, warm air can hold more water vapor than cold air

direct and indirect damage

Wind contributes to hurricane damage directly and indirectly (by making high waves and surge) Wind damage: roof ripped off, walls blow out Wave and surge damage: eroded beach sand and undercut concrete foundation How to protect your house: covering the windows prevents wind from getting inside the structure. People can have special coverings or buy plywood Heavy rain and flooding: Harvey in 2017 had sooo much flooding and just sat over houston and then recharged and rained on it more There were 1,000 year flood events. It was the storm of the millenia in the houston area It was extremely costly Florence in 2018 also caused very extreme flooding, 20 inches of rain plus. They made people move inland because they were scared of storm surge, but it still rained terribly inland and caused a lot of issues in the carolina Rainfall: Water is brought up from the ocean into the atmosphere and cools, cool air cant hold as much water so it dumps rain Heavy rain associated with hurricanes can: Cause widespread flooding causing property damage, drowning It can wash out infrastructure (power, water, sewer) sewer can fill up and contaminate tons of water so theres no clean water It contaminates water supplies It can also trigger landslides Slow moving, low intensity hurricanees can have much worse flooding than faster moving, high intensity ones. Even a category one can be worse if its slow moving Flat, low lying areas drain slowly and magnify the problem. The water cant really move out, so it stagnates and builds If one hurricane follows another, flooding is worse as soil is already saturated

Hadley cell

a large-scale atmospheric convection cell in which air rises at the equator and sinks at medium latitudes, typically about 30° north or south. (see pic)

natural disaster

a natural event that causes significant damage to life on property. Natural disasters occur where and when natural processes cause casualities and/or destruction of property. Nat. disasters are the meeting between natural hazards and society -The natural disasters with the highest percentage of occurrences worldwide are 1. Floods (the damage from hurricanes is more from floods than winds) 2. Storms 3. Earthquakes

Natural hazard

a natural process that poses threat to human life or property Ex: -geophysical (earthquake, dry mass movement, volcanic activity) -hydrological (flood, landslide, wave action) -meteorological (storm, extreme temperatures, fog) -climatological (drought, glacial lake outburst, wildfire) -biological (animal accident, epidemic, insect infestation) -extra-terrestrial (impact, space weather)

Cali earthquake 1989

also a 7 on richter scale, struck the SF bay area (pop, 10 million ppl) only killed 63 people SF was more prepared structurally for this kind of event

Dissipation of hurricanes

as hurricane moves over land, it quickly loses energy due to loss of its "battery" : no warm water underneath, also topography disrupts convective cells Can also dissipate in open ocean as it moves pole-ward over cooler water Also strong winds from the north can hit hurricanes Harvey hit land, then went back in the water and recharged and then just sat over the coastline for days

Hurricane Harvey

hit houston TX and was the 2nd most costly disaster in US history 71% of economic damage from disasters in from weather related (natural) disasters (look at slide) it hit land, then went back in the water and recharged and then just sat over the coastline for days

cyclones

rotating masses of low pressure air Hurricances are just one type of these

Tropical depression (stages of hurricane development)

system of clouds and thundrstorms with a defined surface circulation wind speeds less than 38 mph/ 68 km/h

Hurricane "wake"

the colder sea surface temperatures that hurricanes leave behind them in their path as they travel. The heat has been sucked out of the ocean by the storm. This is one of the most efficient ways of heat transfer -Heat transfer from ocean surface to the atmosphere •Raindrops and cloud cover

Hurrican katrina (2005) case study

the levee failed in New orleans because the water came up super high (i think?) and the levee broke Gulf of mexico storms are reallt dangerous because the gulf of mexico is 2-5 degrees warmer than the other stuff so it really fuels these storms It went from a 1 to a 3 category really quickly Lots of people died in mississippi as well. The mississippi river delta was eroding, sinking Katrina was a category 3 when in made landfall early in the morning august 29 2005 The storm surge went west in lakes bourne and pontchartrain which made tons of water push up against the levees, Its also water adding to water when the hurricane hits a lake so it gets problematic for flooding The storm surge was up to 25 feet New orleans was also pretty flat, like florida, theres no sea cliffs About 70% of new oreleans lies below sea level A series of levees keeps water out Drainage canals and pumps get rid of rainwater But, the power went out in new orleans so none of these drainage systems could be used and they flooded too Everything was failing when the levees broke Levees and floodwalls failes, mostly overtopped, then eroded, homes flooded Flood depths ranged up to 4.5 meters plus (like 15 feet i think) The water also couldnt be drank because it got ruined with sewege. It was like being in a desert Everything east of the 17th st canal was flooded Highest parts,including the frenh quarter, were on the old natural levees of the mississippi river People went to the superdome for safety There was a huge line to get in, the superdome was surrounded by water so it was hard to get there People were on cots inside of there They were trying to get food and water etc 1361 people were killed 250,000 jobs were lost Associated loss of tax revenue to city and state Costs were around $200 billion estimated $40 billion private insurers $60 billion for the government Like a hundred billion for personal losses i think The population before was about 485,000, dropped to 230,000 right after the storm and now at about 400,000 Many people who evacuated didnt move back, the people who have moved there since are mostly new The levees have been rebuilt What went wrong in the response? Why did so many people die Many people misunderstood the risk due to their previous expereice with storms that were not as bad, chose to stay They saw that it was a category 3 and thought it wasnt a huge deal They didnt evacuate for one because If they evacuated and nothing happened, people wouldnt trust the weather anymore Houses could be robbed and looted when evacuated People in new orleans didnt believe it would be that bad basically But the main story is that many people without transportation were left stranded in New orleans- highly disproportionate effect on the poor and elderly Extreme lack of appropriate planning at the federal level Communication failures; inadequate staging of food and medical supplies, botched evacuation Poor coordination between FEMA, state and local governments

Tropical storm hazards

wind, rainfall, storm surge Wind contributes to hurricane damage directly, and also indirectly (by making high waves and surge) Wind can blow off roofs, flying debris is extremely dangerous, it can be like a tornado Why do just the roofs lift off of buildings? The wind comes up underneath your eves (?) or through an open window and pushes the roof off See pic: storm surge can push into the pile of sand your house is built on and then the house cane collapse. You want to build your house on top of some concrete. Pilings need to be deep See pics Your roof is like an airplane wing Roofs need to be modified for hurricanes. They need to have areas facing every which way