Test 2 Natural Disasters

Trypes of Hurricane Damage

Strong winds: 74-over 157 mph (cat 5); Hurricane Patricia: strongest winds ever

• Wind applies dynamic pressure on buildings and bends/curves around obj creating suction (roof blow off)

Storm surge: wind driven water piled into a bulge of higher water elevation in front of a hurricane

• Saffir-Simpson Hurricane Intensity Scale: combines wind and storm surge characteristics to assess intensity of the hurricane

Waves: shear between strong winds and ocean produces more waves

Rains, flooding, and landslides

o Worse for slow moving hurricane

Subsequent tornadoes (only in some instances)

What are the most deadly and costly natural disaster

Hurricanes are the deadliest and most costly storms on the Earth. Since 1980, eight of the top 10 most expensive disasters are from hurricanes, costing a total of $730 billion in damage.

6 of the top 10 deadliest natural disasters in the U.S. are hurricanes.

Hurricane

a large tropical storm spiraling around a central low-pressure center over the

ocean. These storms can have sustained winds exceeding 74 miles per hour.

Wind Direction in Hurricanes

In low pressure systems with no spin, wind would flow directly towards the lowest pressure, converge, and rise.

With spin, the Coriolis Force deflects wind to the right, producing an overall counter-clockwise rotation of the wind. But with friction slowing the flow, diminishing the Coriolis Effect, wind actually spirals towards the center and up.

Parts of Hurricane

The Eye: a cloud free circular area surrounded by a shield of cirrus clouds

o Approx. 6 – 40 miles wide

The Eye Wall: the dense, upward flowing, rapidly spiraling clouds along the eye; tapers downward like a funnel

o Heaviest rain falls from the eye wall at the center of the storm

Spiral Rainbands: arc-shaped cloud banks of tall, aligned thunderstorms curving from

the edge of the storm toward the eye

o Gets sucked inward

o Not much rain between the bands (These are regions of descending air)

Inner Core: air loops completely around the eye of the hurricane

Outer Zone: loop is incomplete and space between rain bands increases

o Inner core and outer zone divided by the principal rain band (the widest and most

continuous)

Are hurricanes static?

No they are constantly changing

Intensity increases and decreases

• Storm lines bulge or shrink

• Eye walls contract and regenerate

How can you tell the speed of a hurricane

Storm’s forward motion is the speed of eye relative to ground surface:

• If the storm is moving towards you, the total wind speed is the wind speed PLUS the

speed of the forward motion

• If it’s moving away, the total wind speed is the wind speed MINUS the forward motion

speed

Hurricane energy

Heat (thermal energy) drives air flow in hurricane

Only warm, tropical ocean water can accelerate winds to hurricane speeds.

How does warm water transfer heat into the base of the atmosphere to provide energy to a hurricane?

The Latent Heat of Vaporization is the heat required to convert a unit mass of a liquid

into vapor without a change in temperature

• When water evaporates and rises, it is carrying “stored heat” with it

• When water vapor condenses at higher altitudes, the heat is released and warms the

surrounding air

• Warmer, moist air now has lower densities and continues to rise (BECOMES UNSTABLE!)

• Condensation of water vapor to liquid water gives off heat > Keeps parcel warm and buoyant

Positive feedback loop hurricane

Once a hurricane forms, it produces conditions that provide it with more energy, so it keeps getting bigger and stronger.

Atmospheric Instability in Hurricanes

If an air parcel is saturated:

• Water vapor condenses as it rises

• Rising saturated air parcel stays warmer than surrounding air

• It keeps rising and thunderstorms can occur

• Unstable air produces an updraft, where air blows vertically upwardH

Intertropical convergence zone

Typhoons and cyclones form from convergence of trade winds just north of the equator.

Tropical disturbance

Easterly wind waves in Atlantic ocean create areas where slower winds are “bent” under faster flowing winds and cause lifting. As winds curve North on the east side of the wave, they are slower, so they lift faster air.

cluster of thunderstorms that grows in the tropics (between 5 and 30 degrees) and lasts for more than a day. This cluster of storms is called an organized convection.

Hurricane Evolution

1) Trade winds over the Indian Ocean pick up moisture

2) Moist winds from Indian Ocean blow over Ethiopian Highlands (mountains) forming

easterly wind waves

3) Tropical disturbance leaves Africa and goes out over ocean

4) Expansion causes air at higher altitudes to diverge, causing rising center and development

of a low pressure center.

5) Thunderstorms in disturbance start to rotate around the low-pressure center.

6) Positive feedbacks produce more intense wind and rain, producing more intense wind and

rain, producing more intense pressure drops

7) Pressure continues to drop in center, creating even more intense wind and rain

8) Centrifugal force and dropping pressure continue to organize the storm, including

“pushing” the eye clean

9) HURRICANE!!

Tropical Depression

A tropical disturbance building over the ocean that begins to circulate around an area where atmospheric pressures have dropped significantly below the pressures of the surrounding area

creates a vortex around a low-pressure center with maximum sustained winds between 23 and 38 miles per hour.

Tropical Storms

A tropical depression that intensifies (or a hurricane that weakens) to support sustained wind speeds at 39 – 74 miles per hour

What controls the track of a hurricane?

• Strong semi-permanent high pressure systems

o Locations: Bermuda, Azores High

• Prevailing winds

Atlantic hurricanes continue west to Central America and the Gulf OR turn north along the east coast. Once it hits land or cooler water, it loses energy. However, the hurricane can still carry large amounts of rain up as the disturbance continues on its way

How do you keep a Hurricane going?

1. Keep it over warm, evaporation water

   2) Keep it under relatively slow high-altitude winds

How do you destroy a hurricane?

1 Storm moves over higher latitudes and cooler water

2) Storm moves over land. This means no more evaporation (no more fuel)

3) Storm runs into strong high-altitude winds (wind shear)

What can be done to better mitigate hurricane damage?

Zoning: minimum setbacks along vulnerable shorelines

Protective landscapes: beach dunes and coastal wetlands blunt surge, wave, and wind

impacts

• Hillslope forests limit landslides.

Building codes: water and wind resistant building methods and materials

o Reinforced Stilts

• Expensive, so not often used in poorer areas

How to prep for hurricane

Monitor the storm

• Secure the property

• Evacuate

• Shelter in place

Where is the most amt of rain in a hurricane

Eye wall at center of storm

Rain decreases with distance from the eye

Not much rain between bands (descending air)

Climate

weather patterns (temperature, moisture, etc.) over a large area averaged from data

collected over decades to centuries or more. Climate is not the same as weather on any particular

day.

Global Climate Change

Long-term climate change: these processes take millions to tens of millions of years in

scale

o Earth has experienced multiple changes in climate over the last 4 billion years

Short-term climate change: tens to hundreds of thousands of years in scale

o The past 15,000 years (the Holocene)

▪ Warming led to deglaciation; temperatures still fluctuate

Temperatures were trending down from year 1000 to year 1900 with a rapid increase in temperatures over the last 150 years. CO2 levels are higher than the entire preceding 800,000 years

Direct measurements for Climate Change

Direct measurements are data or observations we make directly on the item we are studying:

• Temperatures

• Dissolved nutrients

• Body length

• Radiation

• Car or baseball speedPro

Proxy Measurements for climate change

Proxy measurements are data or observations that can stand in for DIRECT measurements:

• Crop yield: weather/drought

• Tree rings: moisture/temperature

• Deer harvest: deer population

• Scientists use proxy data to describe climates beyond the reach of thermometers and

other “technology”

Direct Data for climate change

Ice cores: we can directly measure atmospheric CO2 from bubbles trapped in ice cores

Oxygen isotopes

o During Warmer periods, precipitation releases 16O and 18O,

▪ 18O gets stays in ice

▪ More 16O returns to ocean via runoff

▪ 18O / 16O is lower in the ocean and higher in ice.

o During Colder Periods, less 18O is evaporated and more 16O stays in the ice

▪ Ice has more 16O, so 18O / 16O ratio is lower

▪ Ocean has relatively more 18O so 18O / 16O is higher

Why do we think climate change and carbon emission are linked?

Natural impacts on the climate, such as solar output, volcanic activity, and Milankovitch

Cycles don’t account for rise in temperatures we observe after the 1920. But if you add in the

human factors (e.g., Greenhouse gas output from fossil fuel burning), predicted/modeled

temperatures align with the observed temperatures. We can then project these calibrated models

to the future. CO2 concentrations (measured directly from Air bubbles in ice) are directly related

to temperatures estimated from 18O/16O isotopic ratios.

Carbon cycle

flow of carbon between the atmosphere, rocks, oceans, and biosphere.

The largest reservoir of carbon is in the lithosphere in sedimentary rocks. When we release this carbon, the natural control mechanisms work very slowly to return it to the lithosphere

Long-term carbon cycle

locked away in rocks and fossil fuels

1) In the long-term reservoir atmospheric carbon dioxide reacts with water and

minerals in rocks to form calcium bicarbonate.

2) Calcium bicarbonate dissolves in water which enters rivers and ends up in the

ocean where it becomes shells of various marine organisms (small and large).

3) When these organisms die, the shells accumulate on the ocean floor and are

eventually transformed into rocks (limestones) and hydrocarbons.

4) Carbon re-enters atmosphere (short term cycle) if rocks are heated or pressurized

allowing CO2 to volatilize and escape (eg., volcanos, coal burning)

▪ Once locked away, carbon may be stored for millions of years

Short-term carbon cycle

takes months to centuries to recycle carbon dioxide through

the short-term reservoir

1) Atmospheric carbon dioxide is processed via growth and death of plants, animals,

and microbes

2) Atmospheric carbon dioxide is dissolved in the ocean which helps maintain a

stable pH for life.

How do you get CO2 out of the atmosphere (for long term)?

1. Burial of organic material

2) Weathering of silicate minerals

Co2 in the Atmosphere – Human Impacts

Burning fossil fuels for industry and transportation, from the industrial revolution to today quickly converted CO2 in the rock (long term cycle) to CO2 in the atmosphere (short term cycle) It will take a long, long, long time to get it back to the long term cycle.

Greenhouse gases

Last year 36.4 billion tons of CO2 was released into the atmosphere. Expectation of ~39 billion tons of CO2 for 2022. Emissions keep rising, despite agreements. U.S. use has leveled off. China and India are drastically increasing their use. CO2 levels just keep going up and reached 420 ppm in 2022

Greenhouse Effect

H2O, CO2, and CH4 in Earth’s atmosphere absorb thermal energy and reradiate it, warming the lower atmosphere. Increasing CO2 (and CH4) enhances the Greenhouse Effect, making it warmer.

Forest Loss & it’s Affect on CO2 Concentrations

Forest loss of 3 million km2 between 2000 and 2012.

• Less forests mean less CO2 uptake by plants

• Burnt forests means more CO2 in the atmosphere

What we are measuring to define climate change?

Global temperature rise (thermometer)

o Temperature anomaly: a departure from a reference value or long-term average

Warming oceans

o Temperature anomalies in the ocean

▪ The comparison of current conditions with long term averages show the

oceans are warming

Change in ice volume

• Land ice: glaciers

o Sea ice: has dissipated in area, thickness, and age over the last 40 years

o Snow cover: between 1972 and 2015, the average extent of North American snow

cover decreased at a rate of about 3,300 square miles per year.

Sea lvl rise

• Caused by added water from melting land ice and Expansion of sea water as it warms

Extreme weather and natural disasters

Why is losing ice bad?

▪ Screws up hydrology

▪ Albedo effect

▪ Rise in sea level