weather book questions for exam 2 and final

what is the EF-scale, how is an EF-scale rating assigned to a tornado

"enhanced-fujita" scale it's based on highest 3-second gust speed, and there are lists of damage indicators and degrees of damage

by approximately what percent have the atmosphere's carbon dioxide concentrations increased since the pre-industrial period

40%

what is the difference between a "stepped leader" and a "dart leader"

A stepped leader is the first step of the lightning cycle of sorts where the particles from the cloud branch out as lightning trying to find the path of least resistance to the ground, and the dart leader is after the return stroke and another streak of lightning follows the same path as the stepped leader lightning strike did

how does a tornado warning differ from a tornado watch

A watch means the conditions are particularly favorable for the development of a tornado. while a storm is in progress a warning will be issues when a tornado is believed to be present in that area

summarize key differences associated with colorado cyclones and alberta clippers

Alberta clippers are colder and produce less snow and its snow is typically drier and easily windblown. Colorado cyclones have stronger winds and deeper low pressure

what are boundary intersections, and what role do they have in supercells

Boundary intersections are the locations where two boundaries (fronts) meet. Supercells have a tendency to develop at these points of intersection

where do blizzards typically form relative to the center of a colorado cyclone? what about alberta clippers

Colorado cyclones-the storm will develop in eastern CO and the blizzard forms northwest of CO for example in North Dakota Alberta clippers- over the great lakes

which two states experience the most tornadoes per 10,000 square miles? which state experiences the greatest number of strong to violent tornadoes per 10,000 square miles

Florida then Oklahoma. and the most violent tornadoes occur in Oklahoma

what trajectories do hailstones typically follow between the hail embryo curtain and the ground

It flows upward through the updraft while collecting supercooled water, floats in the center until it gains enough weight until winds aloft carry it northeast where it begins to rapidly fall

how does the national weather service determine if a thunderstorm is severe

It's considered severe if it has potential to threaten lives and property. that's if it has one of more of these: hail with a diameter of 1+ inch, winds or gusts of 50 knots (58 mph), or a tornado

Is a threshold used to define the occurrence of a heat wave? explain

No because it depends on the average climate in that area

why are MCSs important to the central plains

They produce much of the summer rainfall in the central plains

what is a supercell thunderstorm, what characteristic distinguishes supercells from other types of severe thunderstorms

They're the most intense thunderstorms and they always rotate

shore-parallel bands

a single precipitation band that aligns approximately parallel to the shoreline along the long axis of a lake in lake-effect storms over the Great Lakes

what is a mesocyclone? what is a typical width of a mesocyclone

a small scale cyclone typically between 2-10 km in diameter

what is the tornado vortex signature in a radial velocity field obtained from doppler radar

a tiny area sometimes as small as one pulse volume, which is the smallest volume of space a radar can see, will show up with unusually large velocity in the opposite direction

approximately how long and how wide is a typical lightning stroke

about 3 miles and 2-3 cm in diameter

what are the two broad types of damage caused by hail? how do the annual damage totals in these categories typically compare in the U.S.

agricultural, and structural, agricultural is higher than structural because most large hail falls in the high plains

vortices

air circulations that look similar to a hurricane on radar with an eye and an eyewall of sorts and spiral snow bands. the diameters of these range from about 6-60 miles (10-100 km)

how does a landspout tornado form

also called a non-supercell tornado, converging fronts cause a spin and a cloud moves over this spinning air

what is lightning

an electrical discharge in the atmosphere, a form of static electricity

how does the apparent temperature differ from the heat index

apparent temperature takes into account air temperature, relative humidity, and wind speed, and amount of radiant energy while heat index only takes into account temperature and humidity

what is the characteristic signature of a tornadic thunderstorm in a radar reflectivity image

as the rear flank downdraft wraps around the echo-free base of the updraft the echo on the radar appears like a hook and the tornado is usually located towards the tip of the hook

how has the northern hemisphere's temperature varied during the past century

averages vary by year but the general trend has been exponential growth

how can a charge distribution develop on a precipitation particle that has no net charge

because all conductors even neutral ones have different arrangements of atoms causing exchange when they are brought together

why does the national weather surface not issue hail-specific warnings

because it's hard to know if a storm will produce it or not and when/where it will fall if it does

give two reasons why solar heating of the earth's surface varies seasonally

because of the 23.5 axis tilt, and the amount of atmosphere through which the sun's rays pass

why is supercooled water important to the formation of hail in a thunderstorm

because once ice particles form near the periphery of the updraft the end up collecting supercooled water which becomes ice on contact with the ice particles and forms graupel (which is like a snowball) which will turn into hail

why does the wind chill temperature underestimate the body's heat loss during a blizzard

because when snow lands on exposed skin it draws heat from the body to get the latent heat it needs to melt the snow, and when the moisture from the melted snow evaporates it draws more latent heat from the body to do so

how is the transition from winter to summer likely to change the frequency of thunderstorms in a global warming scenario

because winter seasons will become shorter and thunderstorms are more likely in the spring and summer there will be an earlier onset of thunderstorm season

what types of charged particles are found in thunderstorms

both negative and positive but mostly negative because the storms draw negatively charged particles out of the atmosphere

before the advent of the WSR-88D doppler radar network, what was the primary means of tornado detection

by a network of "storm spotters" who are trained volunteers who report dangerous weather conditions and tornado locations

where do blizzards occur most commonly in the united states

central far north (minnesota and the dakotas)

what distinguished the heatwave of july 1995 from previous heat waves in the midwest

chicago heat wave! there was extremely high, record breaking humidity levels, very high pressure

what are the three ingredients necessary for a blizzard to form

cold temperatures, wind, and snow

what are the long-term drivers of climate change

continental drift, earth's orbital variations. and solar variability and atmospheric variability can be both short and long term

is greenhouse warming expected to be greater of the continents or the oceans, why

continents because the oceans are not able to mix the heat to greater depths

what type of damage and injuries typically occur due to hail

damage to vehicles, roofs and siding. can cause death (either by hitting the head, or panic)

on which side of the great lakes' does lake-effect snow typically occur

downwind, to the south and east of each lake

how is global climate change expected to impact lake-effect snow

due to enhanced warming in the north there is likely to be a decrease in lake-effect snow. this is complicated by the probability of less ice cover on lakes which would increase the probability but it is still most likely that lake effect snow will become less probable.

what factors contributes to the 2011 heat wave in the U.S.

extremely high humidity in the northern and eastern states, south central states had been in a dry winter causing a drought, while the other states had excessively moist winter. both of these situations exacerbated heat wave conditions in their respective areas, atmospheric circulation pattern-large flow of warm air

where is hail generally found on the ground relative to a thunderstorms strongest updraft

flanks the updraft on the east and northeast side

what is "bead lightning"

following a lightning stroke lightning channels sometimes break up very briefly into a series of luminous beads- these are pretty much impossible to see with the human eye because it happens so fast

distinguish between freezing rain, freezing drizzle, and ice pellets

freezing rain forms from the melting process, freezing drizzle forms from the supercooled warm rain process, and ice pellets only partially melted in the first place and re-froze completely before hitting the surface

where in north america is freezing rain most common, where is freezing drizzle most common

freezing rain is most common in the northeast us and eastern canada, freezing drizzle is most common in the north-central of canada and in a line down the center of the us with a hotspot in north texas

how might global climate change affect the frequency and intensity of blizzards in the great plains

frequency and intensity would likely decrease in the great plains

where are high and low pressure systems located relative to the great lakes during a lake-effect snow event

high pressure in the north central us and low pressure in the north east us

how large are frontal squall lines, how long can they last

hundreds of kilometers long , they can last many hours to days

where in the U.S. does large hail occur most frequently

in the agricultural areas of the high planes, in a straight line down to a hotspot in northern texas

where are the regions of positive and negative charge found in a thunderstorm just before a lightning stroke

in the bottom of the cloud there is an accumulation of negatively charged particles and on the ground there is an abundance of positively charged particles

why might the general public be concerned with freezing precipitation

it can be dangerous for driving or walking, and it can cause damage to property

what is the typical width, distance in the direction perpendicular to a front, of the band of freezing rain associated with a frontal cyclone

it does not exceed 100 miles (160 km) and is often much narrower

what is supercooled water

it is when water has not frozen even for either the melting process or warm rain process, and exists as water below 0 degrees and usually freezes on contact with the ground if it's below zero causing glaze

based on computer model projections, how are summer heat waves in the united states likely to change by then end of the present century

it predicted some potentially catestrophic heat waves in chicago and paris, and more humid heat waves. summers will be warmer, and likely nights will be much warmer because of humidity

what advantage will polarization radar give to forecasters in the future

it's capable of distinguishing areas of hail from areas of heavy rain, meaning they could issue hail-specific warnings

what is the difference between lake-effect snow and lake-enhanced snow

lake-enhanced snow is when the moisture from the lakes contributes to snowfall from an already formed cyclone. often falls in areas like chicago that normally do not get lake-effect snow due to wind patterns

what are the three reasons why oceans have a larger capacity to hold heat than land

land can get hotter from the sun but loses its heat faster. the ocean loses heat via evaporation aka latent heat release

why do ground blizzards occur

light dry snow + high winds causes the snow to blow a lot in the first couple of tens of feet near the surface

what are the names of the two processes that cause freezing precipitation

melting process, or supercooled warm rain process

what type of severe weather do supercells produce

most tornadoes are produced by supercells, most large hail, and damaging straightline winds

where is the jetstream typically located during a heat wave over the U.S.

must generally be far north of the area affected by the heat wave

where do normal and positive polarity lightning strokes typically originate and terminate in a cloud, which type is most common and why

normal strikes originate in the bottom of the cloud which is negative and the ground below is positive, whereas with a positive polarity strike starts in the anvil which is the upper, positively charged part of the cloud underneath which is negatively charged

during what time of year are frontal squall lines most common

november?

what is meant by the term "cold air damming" where does it typically occur

one way it can develop is: as an arctic airmass moves across eastern US and its high pressure center moves towards the north atlantic a warm, moist easterly flow moves over it and forces cold air between the mountains to the west and the offshore flow to the east It occurs on the eastern side of the Appalachian mountains

wind-parallel rolls

parallel band of precipitation that form over he great lakes in winter as airflow develops alternating rising and sinking motions perpendicular to the direction of the wind

what is an ice age, how long have the major glaciations of the Pleistocene lasted

periods of expanded continental ice sheets, polar ice sheets, and mountain glaciers. major glaciations have lasted a couple million years

is global climate change expected to increase the frequency of thunderstorms

scientists determined that more research will need to be done because all the small effects and contributors to thunderstorms are very hard to predict and study

how large are MCSs and how long do they typically last

the bow echo can be 90-125 miles and the precipitation can be 60-120 miles. The clouds can cover an area the size of a large state. they last for a couple of hours. maybe several maybe about 7

do global climate models simulate thunderstorms, why or why not

the current models do not have the capability to simulate thunderstorms but they likely will be able to in the future

describe the airflow in a hadley cell

the easterly trade winds meet in the intertropical convergance zone over the equator and air flows up and away- north and south- then descends in the subtropical highs

what is a hail embryo, where is a hail embryo curtain in a supercell thunderstorm

the ice particles that occupy the center of hailstones and serve as cores for their initial growth, the embryo curtain is found in an hook shape over the BWER to the stronger side and coming down in the hail cascade

what is the importance of boundaries in thunderstorm development

the lifting that forms thunderstorms, occurs along boundaries between air masses

what is the primary driver of the earth's climate

the unequal distribution of heating from the sun

how has global precipitation changed since 1900

there has been more precipitation in Canada, the U.S., Australia, most of europe, but decreased in northern africa and west coast of south america , southeastern asia, and parts of russia. general trends of dryness in the tropics and wetness other places

what are aerosols, how do they affect the atmosphere's energy budget

they are small particulates in the solid or liquid phase- atmospheric aerosol includes dust, sea salt particles from sea spray etc. they can both absorb and reflect radiation so it depends on the content of the aerosol

along what types of fronts fo frontal squall lines typically form

they form in the warm moist air ahead of surface cold fronts and dry lines or just ahead of an upper level front

where and when would you expect ordinary thunderstorms to form

they form within an airmass (not along the front) sometimes they form along a weak boundary. usually form during hot afternoon like in the warm humid summer in southern and eastern U.S.

what type of forecast product does the storm prediction center routinely issue for hail

they issue forecast maps that show the probability that hail one inch in diameter or larger will occur within 25 miles of a location

why is wind shear important to a severe thunderstorm

thunderstorms require vertical wind shear to form

what type of severe weather is most common with MCSs

tornados

what environmental condition is required for supercell thunderstorms to acquire rotation

vertical wind shear

where within the circulation of a cyclone on the plains does upslope flow occur

when a cyclone moves west from the mississippi to the rockies, where the rise in elevation is very gradual

how does a tornado family develop

when a tornadic supercell goes through lifecycle multiple times and produces multiple tornadoes

why is it often clear on the upwind shoreline of a lake during a lake effect snow event

when air crosses the downwind shoreline friction causes convergence forcing the air upwards and more snow falls. but air has not gathered enough moisture from the lake when it is still upwind.

what is the physical process responsible for thunder

when lightning goes through the air, the air is heated to 54,000 degrees fahrenheit causing the air to expand explosively creating a shockwave that crashes into sound waves.

explain physically the difference between dry and wet growth regimes of hail

when the graupel is collecting supercooled water and the surface of the hailstone stays below zero degrees (because of the rise in temp due to latent heat) then it's the dry growth regime. in the wet growth regime the surface temperature becomes above zero and there's liquid water on the surface of the hailstone.

at what altitudes in a thunderstorm does hail growth normally occur, what parameter determines these altitudes

where the supercooled water is found between altitudes where the temperature ranges from 0-15 degrees celsius

describe typical tornado characteristics such as width, range of wind speeds, and time on the ground

width between 50-800 meters, wind speeds from 65 mph-over 200 mph, most tornadoes are short lived and stay on the ground for less than an hour but some stay for longer

how is hail damage related to wind speed

wind speed gives the hail horizontal force meaning it can do more damage to a vertically oriented plant (most crops)

what are the three ways that lake-effect storms typically organize

wind-parallel rolls, shore-parallel bands, and vortices

what is urban heat island effect

worse heat in cities because: less plants=less moist soil to evaporate and cool the air, asphalts/concrete store greater heat than dirt, combustion from machinery and cars, tall buildings reflect solar radiation

what type of warnings does the national weather service issue for blizzards and what are the criteria used

-Blizzard warning-when winds are expected to exceed 35 mph (30 knots) or falling/blowing snow will reduce visibility to less than a quarter of a mile for 3+ hours. -Stockmens warning- severe winter weather threatens cattle in major ranching areas -Travelers warning-conditions make travel difficult or impossible

what four factors favor the development of a heat wave

1. an absence of polar air masses that might move into the region from the north or west 2. strong heating of the surface 3. dry ground 4. amount of vertical mixing of air

list 5 factors that affect the level of heat stress experienced by the human body

1. humidity 2. radiant energy 3. wind speed 4. atmospheric pressure 5. temperature

list 6 factors that influence the amount of snow that falls during lake effect snow

1. temperature of the lake 2. temperature of the air crossing the lake 3. wind direction 4. wind speed 5. amount of ice cover on the lake 6. topography downwind of the lake

what are the three proposed mechanisms for tornadogenesis

1. the development of mid level rotation:mid-level mesocyclone 2. the development of low level rotation: low-level mesocyclone which is associated with the formation of the wall cloud 3. development of rotation of rotation at the ground

which decade of the 20th century had the highest average summer temperatures in the united states

1930s