Natural Disasters Final - Pitt

The general topography

The local climate

regions of already severe thunderstorms

areas where air is undisturbed by mountains

Texas, Oklahoma, Kansas, Nebraska, Iowa, Missouri, Illinois

Alaska

texas

florida

It is gradually shifting eastward

75 yards

1-4 miles

5 minutes

25 mph

spring to early summer (but this seems to be shifting with climate change)

Late afternoon to late evening - Time of maximum ground and atmospheric heating

Combinations of opposing wind patterns (dry and wet)

the west

the southeast originating in the golf of mexico

warm/wet air provides energy

Large thunderstorms pull warmer air upward from low levels

winds form cyclonic rotation parallel to the ground

an cause a roller to tip into a vertical position

Tornado is born upon touchdown with the ground

Called tornado families or storms

caused damage to 13 states

148 tornados touched down in about 16 hours

307 killed

Inside a twister can be as low as 3” mercury (measured on a barometer)

generally SW to NE

Combination of the prevailing wind direction from the west

The CCW rotation of the tornado

Varies from EF0 to EF5

Precise wind speed numbers are actually estimates based on damage after the storm and not measured directly during

light damage some damage to chimneys; branches broken off trees; shallow-rooted trees pushed over; sign boards damaged

Moderate damage. Peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos blown off roads

Considerable damage. Roofs torn off frame houses; mobile homes demolished; train cars overturned; large trees snapped or uprooted; light-object missiles generated; cars lifted off ground

Severe damage. Roofs and some walls torn off well-constructed houses; trains overturned; most trees in forest uprooted; heavy cars lifted off the ground and thrown.

Devastating damage. Well-constructed houses leveled; structures with weak foundations blown away some distance; cars thrown

Incredible damage. Strong frame houses leveled off foundations and swept away; automobile-sized missiles fly through the air in excess of 100 meters; trees debarked

called TOTO

Designed to get swept up into a tornado and measure all the atmospheric parameters of a tornado from the inside

Scientists had to race to get ahead of a tornado and place the 400 pound cylinder squarely in its path

Never actually worked

Monitors regional weather conditions every morning

Issues a risk warning for severe weather later that day

Use of doppler radar

Measures the frequency change of objects moving away from the antenna

Interpets mesocyclones

Operated on a mobile platform to image nearby tornadic activity

Can get much closer to the tornado to image it more clearly

no practical efforts - Most injuries/death occur from flying objects or being picked up and thrown around

can be placed in homes or backyards to keep residents safe from tornados - but does nothing to protect the house

Worst on record until 2020

including Epsilon and Zeta (at the “end of the season”), there were 27 named storms, surpassing the record of 21 set in 1933

10 named storms, 6 hurricanes and 2 major hurricanes

impact larger areas

have stronger winds but affect a smaller area

Fatalities over time have gone down but insured property loss has skyrocketed

hurricanes

typhoons

cyclones

1. tropical wave

2. tropical depression or disturbance

3. tropical storm

4. hurricane

Initial low pressure disturbance

Unorganized

Moving west

Winds <20 mph

Moving mass of thunderstorms

Starting to organize

Winds <39 mph

Gets named

Distinct rotary/cyclonic motion

Winds 39-74 mph

Well defined circular structure

Central eye of low pressure first forms

Winds > 74mph

off the coast of africa

from june-november

calm wind patterns

Warm water (>80 degrees) - Provides large amounts of evaporation and fuel for the storm

Caused by the interaction of westerly mid-lattidue winds with the easterly trade winds

Allows a pathway to form for moisture transport from sea to upper atmosphere

Release of heat energy from the condensation of the water

Global warming estimates for a 1 degree celsius increase in sea surface temp

stronger winds → more cylonic motion → draws up more moisture and heat from the sea → stronger winds

Rain bands of thunderstorms spiraling around a central (low pressure) eye

moist, warm air is drawn up in the eye wall and within the spiriling arms

low pressure

Greatest winds are in the eye wall

Measured 1-5

Function of wind speed, storm surge, potential damage

Large volume of rain/runoff prior to landfall of the hurricane

Two types: flood surge and ebb surge

water brought onto the land by the storm

water floods back off the land to the sea

Force of the waves

Hydraulic lift (upward force) under structures

Reflected wave energy from other man-made structures

the speed of the storm, the winds whipping around the eye

speed of the storm’s counter clockwise winds

speed that the storm is moving over ocean/land

influenced by the upper-level winds, regional temperature, other weather Patterns

both of these can combine to cause more damage

the HWV combines with the SCV

produces the most damaging winds

the SCV is subtracted from the HWV

results in the least damaging winds

storm moves along the coast

weaker winds over the land and stronger winds over the ocean

by two storm surges: flood surge ahead of the storm and an ebb surge behind it

results in moderate-heavy damage along the coast

less damage further inland

storm moves perpendicular to coast, moving from the water and onto the land

strongest winds on the right side of the storm (HWV + SCV)

• produces a zone of higher damage off center to the right of the storm track

• less damage to the “left” side of the eye

Since 6-7 hurricanes have formed in the north atlantic every year

2 per year make landfall in the US

Intensity has risen over the past 20 years

Visible and infrared satellite images

Planes flying through the storm center

• Measure vertical structure, wind speeds, pressure, and temperature

create storm track maps

the costliest disaster in US history (until hurricane katrina)

• real estate development along the Florida coast in the 70s and 80s put lives and dollars at risk

• total damage = $27 billion

• 26 deaths directly attributable to Andrew

most deaths associated with the storm surge and strong waves

responsible for erosion and damage caused by floating debris

the costliest and one of the deadliest hurricanes in American history

waited too long to order city evacuation (many were trapped in the city from this)

slow response time from officials

when the volume of river/stream flow exceeds natural barriers and/or the levels of flood preparedness

heavy rain

dam failure

rapid snowmelt / ice jams

deforestation

steep slopes

storm surges during tropical storms / hurricanes

rapid rise and fall of water level

slower rise and fall, but larger area affected

rainfall, infiltration rate (soil types), climate, season, vegetation

urbanization, slope modification, timber industry, flood control measures, agriculture

housing, agriculture, water supply, transportation routes

bank-to-bank distance

distance from water surface to stream bed

distance from stream head to entrance into a larger water body

volume / time

basic unit of surface water hydrology

highest point between stream drainage basins

relationship between precipitation rate and infiltration rate

• determines how much water remains on the surface

capacity of a soil to absorb water

varies with soil type, soil condition, time of precipitation event

increased run off

flooding potential increases

coarse soil

well-vegetated land

low soil moisture

porous topsoil

impermeable crusts

salt layers

cold weather

Compaction

paved (impervious) surfaces

Erosion

Flooding

urbanization and modification of river valleys = Increase effects of the natural hazards