GEO 005 Exam 3

What happens to warm, moist air when it rises?

It expands and cools, cannot hold as much water vapor as warm air, so it causes the water vapor to condense in droplets and ice crystals, forming clouds

What happens when a cold air mass collides with a warm, moist air mass?

Cold fronts push warm moist air high into the atmosphere and give rise to severe thunderstorms

Which is heavier: dry or moist air?

Dry air is heaver, as is cold air

What causes lightening?

A sudden electrostatic discharge between oppositely charged regions of a cloud or between a cloud and the ground

What causes thunder?

A rapid expansion of air due to rising temperatures to over 50,000 degrees that results in a shockwave

What causes hail?

Ice crystals that travel repeatedly above and below the freezing line, enabling additional water to freeze onto them until they become too heavy for updrafts and fall to the ground

What distinguishes supercells from all other thunderstorms and how do supercells develop?

the presence of a mesocyclone // Giant cumulonimbus clouds that rotate formed when a strong wind shear leads to horizontal vortex that is then rotated into a vertical vortex

Why is hail often found in front of a tornado?

There is an updraft going into a tornado, and a downdraft dropping hail in front of a tornado

Which way does a wind blow near a tornado?

Wind blows towards a tornado feeding the updraft, then blows out from the tornado 100 feet above ground

What are the major components of what makes the midwest so productive for tornados?

1. Cold dry air from the north collides with warm moist air from the gulf to form cumulonimbus clouds, 2. winds from the jet stream cause the cumulonimbus clouds to experience horizontal shear (vortices parallel to the ground), 3. warm dry air from the southwest lifts and rotates the vortices into a vertical orientation, generating a spinning supercell

About how many tornadoes occur each year in the US?

About 1,000

When is prime tornado season in the US?

The spring, when waters from the Gulf of Mexico begin to warm, while cold air masses still descend from the north

How does the Enhanced Fuijita Scale rate tornado strength?

Based on the damage it inflicts, which is then used to estimate wind speed

Can fixed Doppler radar easily measure tornado wind speeds?

No- it can only measure wind speeds a few km above the ground which is good for supercells, but not tornados

Can tornados contain multiple vortices?

Tornadoes cannot split or join, but multiple vortices are common, with each rotating about a larger tornadic center

Where should you take shelter from a tornado if you're outside?

Get inside and go to the basement. If there is no basement, go to a small ground floor interior room without windows

Where should you take shelter from a tornado if you're in a car?

If there is no traffic, drive away at right angles to the direction the tornado is traveling. If stuck in traffic and no obvious shelter, get to a low spot and lie down to avoid flying debris. Do not hide under an overpass!!

What kills people during tornadoes?

Flying objects, not wind

What is a hurricane?

A tropical cyclone, an organization of a large number of thunderstorms originating in the tropics into a massive single rotating storm system// it is an area of low atmospheric pressure characterized by rotating winds// Happens in the northern hemisphere in the Atlantic and eastern Pacific

What is a typhoon?

Happens in the western Pacific

What is a cyclone?

Happens in the Indian Ocean, southern hemisphere

What provides energy for hurricanes?

warm, tropical waters

What happens when hurricanes go over land?

Their winds diminish

When is the primary North Atlantic hurricane season?

August-October when tropical waters are the warmest

Why can cyclones not form on the equator?

Because there is no Coriolis effect, so groups of thunderstorms cannot organize themselves into a cyclone

What wind and pressure conditions are found in the eye and eye wall of a hurricane?

Warm air rising causes pressure to drop, reaching a minimum at the center of the eye. Hurricanes also cause a rise in humidity, and winds. The highest winds occur in the eye wall as winds cannot penetrate into the eye.
In the eye, there is dry, descending air, wind drop, and pressure drop // The highest winds occur at the eyewall eye→ lowest pressure and wind eyewell→highest winds

What is the Saffir-Simpson Intensity Scale based on?

Wind speed

What is the main way we measure the wind speeds, pressure, and temperatures of hurricanes?

Using direct measurements using dropsondes are the main accurate means to understand the properties of a hurricane. Combined with numerical models, this can help us estimate how powerful a hurricane may get and where it might be heading

What causes storm surges?

Hurricane winds can push water onshore, causing severe coastal flooding → storm surge / they mimic high tides → major cause of death from hurricane // Wind-driven and pressure driven pile up when they approach land

What is the deadliest hazard associated with a hurricane?

A storm surge

What causes nor'easters?

Cold, arctic air collides with and lifts warm, moist air above the Gulf

What are the similarities and differences between hurricanes and nor'easters?

Similarities: both rely on warm water, but nor'easters require a cold front that lifts warm moist air
Differences: nor'easters form in the north Atlantic, hurricanes form in the tropics; snow is only with nor'easters; nor'easters are most common in the winter, hurricanes occur in the late summer; nor'easters rarely form an eye

What were the major components of the 1991 Perfect Storm?

Cold front from the west, nor'easter from the northeast, hurricane grace from the south

Hurricane safety practices

Evacuate if mandatory or you live in a mobile home, high rise, or area prone to a storm surge
If evacuating, leave early to avoid traffic, find hotel occupancies, and have time to change plans
If staying, gather food, water, emergency supplies, and rx drugs bc a hurricane/loss of electricity may last for a while. If your house uses an electrical water pump, fill a bathtub with water
Bring all outside furniture in and consider taping up windows to px shattering
Put all of your valuables into clear plastic bags or watertight bin
Shelter in place as with a tornado

Which cyclone was the deadliest and how many people were killed?

Bhola, Bangladesh, 500,000 fatalities

Can a hurricane change into a typhoon?

Yes, if it travels into the region that has typhoons.

What is unique about the current rise in global temperatures?

The rate of temperature increases more than 1C in the past 50 years- 10x faster than anytime in the past 800,000 years

What is the main reason why the Earth's temperature changes over very long periods of time?

Milankovitch Cycles(changes in earth's orbital pattern):

How has the average amount of energy the Earth has received from the Sun has changed over the past 50 years?

It has remained the same or decreased

How do greenhouse gases cause warming of the Earth's atmosphere?

Greenhouse gases allow visible light to pass, but trap some of the re-admitted infrared light (heat)- short wave passes, but long wave radiation is trapped

What would the Earth be like if there were no greenhouse gases?

The Earth would average only 0F and become completely covered in ice

What percent of the atmosphere the comprises of greenhouse gases?

Only about .05%

What is the current source of most greenhouse gas emissions?

Human greenhouse gas emissions far outpace those from natural sources, with most coming from the burning of fossil fuels. Coal powered plants are the largest contributors of CO2. A single coal-fired power plant can use 10,000 tons of coal per day- the amount carried by a 100-car train

How do aerosols influence global warming?

They are any small particle suspended in the atmosphere that block sunlight- thus causing cooling. Mt. Tambora in 1815 caused global cooling of 0.5C for a year

How does ice influence our climate?

Ice reflects 90% of sunlight and converts only 10% to heat, whereas ocean water is the opposite

What do ice cores tell us about the relationship between global temperatures and greenhouse gas concentrations?

Temperatures and CO2 concentrations are always closely correlated

What do atmospheric numerical models conclude regarding the cause of the current significant rise in global temperatures?

Human facts are responsible for the current rise in temperatures

What is global warming?

The ongoing rise in global average temperatures

What is climate change?

The changes in climate, frequency and severity of storms brought about by global warming

How can climate change influence the weather?

Unusually warm weather in the arctic pushes unusually cold weather to the south

What are some of the effects that climate change is already causing?

Higher temperatures mean more water evaporates, leading to more storms and flooding; glaciers are disappearing world wide

What is the approximate percentage of peer-reviewed scientific papers about the causes of global warming that conclude that humans are the cause?

97%

What is confirmation bias?

The urge to believe only things that confirm what you already believe to be true

What are the areas where legitimate debate/uncertainty still exist regarding climate change?

1. How should we balance environmental and economic concerns?
2. How much will the Earth heat up?
3. What are the best strategies to fight global warming?

Does lightning or humans start more wildfires?

humans // 85% are caused by humans, rest by lightning

Which factors strongly influence the potential for wildfires to start.

1. vegetation (some fuels burn more easily) 2. topography (fires burn faster uphill) 3. weather (hotter and dryer means faster burn)

What is a surface fire?

A grass or brush fire that burns low to the ground // burn more easily and spread rapidly

What is a crown fire?

Flames are carried along tree canopies - driven by strong winds and steep slopes

What are the three stages of a wildfire?

Preignition (heat of fuels causes them to lose moisture causing them to be more combustible), combustion (hotter temp causes fuelt to release gases that lead to a chemical to release more heat) , extinction.

Which wildfire was the largest to occur in United States history?

The GreaT Fire of 1910 // burned 3 mil acres

The original and current policies of the U.S. Forest Service regarding fighting wildfires.

the original: aggressively fight all fires
current: mitigation and management (permit fires to burn in wilderness areas, only fight fires that endanger people or important structures)

The benefits of forest and grassland wildfires.

grassland - prevent trees and shrubs from taking over
forest - fires allow certain seeds to germinate

The difference between a fire weather watch and a fire weather warning.

~Fire weather watch: Potentially dangerous fire weather conditions are possible over the next 12 to 72 hours.
~Fire weather warning: Wildfires are occurring in the general area or will occur in the next 24 hours.

The dangers of burning embers (firebrands) and good wildfire safety practices at home and
while camping.

burning embers are the most common means of spreading a fire in subdivision // good wildfire safety practices: home - remove shrubs, avoid outside burning, fire resistant shingled roof, scattered trees within 30ft of structure etc. // camping: - no cabin surrounded by trees, not a lot of logs, not a lot of shrubs

The purpose of a fireline and a backburn in fighting wildfires

fireline - remove brush and scrape down to the soil along a wide line so that a surface fire cannot
passbackburn - removes fuel from the path of a fire (always set in conjunction with a pre-existing fireline)

Why fire retardants dropped from air tankers are colored red

to mark where they are dropped

. The advantage that helitankers have over air tankers.

more specific targeting, can refill in small bodies of water, some carry water cannons like fire trucks

The main function of a smoke jumper.

To get to and fight remote wildfires before they become too destructive

What fire shelters are designed to do (and not designed to do).

Designed to do: reflect heat, trap breathable air, serve as final effort to survive wildfire
not designed to do: protect against direct, sustained contact with flames

The factors that contributed to the deaths of the Granite Mountain Hotshot crew.

-a sudden downdraft changed the direction of the fire
-the crew did not have GPS to relay their exact coordinates
-the air tanker flying above did not know their location
-nobody knows why they descended out of the black

What is a meteoroid?

small rocks (less than a few meters across) traveling through space

What is a meteor?

small rocks produced when meteoroids burn up in the earth's atmosphere and light up the sky

What is a meteorite?

small pieces of space rock that survive passage through the atmosphere to be picked up in the surface

What are asteroids?

large space rock; up to 100km

What are comets?

an object made of gas, ice, and dust that orbits around the sun

What is regolith?

-layer of loose dust and small particles left over from many impacts
-reason why asteroids have smooth surfaces

Where are asteroids found?

In the asteroid belt between Mars and Jupiter

Is the asteroid belt crowded?

no, it's really huge and not crowded; there is a 500,000 km avg distance between asteroids

About how much all that mass would add up to compared to the Moon?

total mass of the asteroid belt adds up to just 4% of the mass of the Moon

Why are comets referred to as dirty ice balls?

they are a mixture of ice and rock

What causes comets to have tails?

as a comet approaches the sun, solar radiation causes the ices to vaporize and stream out of the nucleus, carrying dust and gas with them, this then becomes the tails of the comets

what is the direction of the gas tail relative to the Sun?

it is pushed away from the sun by solar wind