Block 3 Exam (Thunderstorms)

Which of the following are aspects that may classify a storm as severe?

• Diverging Winds

• Produces a tornado

• Surface winds of 50kts or greater

• Large Hail (3/4 inch)

• Produces a tornado

• Surface winds of 50kts or greater

• Large Hail (3/4 inch)

All thunderstorms require

• Hot, humid air

• Rising air

• diverging air aloft

• surface heating

• Rising air

An elongated cloud that forms just behind the gust front is a roll cloud

• True

• False

• True

Ordinary (Airmass) thunderstorms only last about 30 minutes to one hour and begin to dissipate:

• when solar heating at the ground begins to decrease

• Lightning neutralizes all the electrical charge in the cloud

• when the downdraft spreads throughout the cloud and cuts off the updraft

• when all the precipitation particles turn to ice

• when the downdraft spreads throughout the cloud and cuts off the updraft

Conditional instability is a favorable condition for thunderstorm formation.

• True

• False

• True

A hook echo on a radar screen often indicates:

• a thunderstorm with very frequent lightning

• a rotating anvil cloud at the top of a thunderstorm

• a developing hurricane

• the possible presence of a tornado producing thunderstorm

• the possible presence of a tornado producing thunderstorm

Which of the following factors is most important in determining the strength of a tornado?

• Diameter

• Duration

• Central pressure

• Air temperature

• Central pressure

A funnel cloud characteristic of a tonado is principally formed by:

• Condensation of water vapor in air drawn into the low pressure core of the tornado

• water drawn up from the sea surface into the cloud

• clouds beubg funneled by downward air currents coming out of a cumulonimbus cloud

• dust and dirt picked up from the atmosphere

• Condensation of water vapor in air drawn into the low pressure core of the tornado

The most frequent time of day for tornadoes to form is the:

• Afternoon

• Middle of the night

• Early morning just after sunrise

• Evening at sunset

• Evening at sunset

If a tornado is rotating in a counterclockwise direction and moving toward the northeast, the strongest winds will be on its _____ side.

• Southeastern

• Northeastern

• Southwestern

• Northwestern

• Southeastern

Most tornadoes only last a few minutes, but some have existed for several hours

• True

• False

• True

Most tornadoes move from:

• Southeast to northwest

• Northwest to southwest

• Southwest to northeast

• South to north

• Southwest to northeast

About equal numbers of clockwise and counterclockwise rotating tornadoes are observed in the United States every year

• True

• False

• False

The wind speed of a tornado is greater on one side than the other.

• True

• False

• True

Weak tornadoes sometimes form along a thunderstorm gust front

• True

• False

True

The storm surge associated with a hurricane is usually on the ____ side of the storm.

• West

• East

• North

• South

• North

In the Tropical Latitudes, seasons are defined by ____.

• Temperature

• Date on the calendar

• Precipitation

• Dewpoint

• Precipitation

The highest wind speeds are on the____ side of a hurricane.

• South

• West

• North

• East

• East

How many spiraling rain bands does a hurricane usually have?

• 1

• 4

• 3

• 2

• 3

If a front crosses into the tropics from the mid-latitudes, the temp difference is minimized but it can produce enough winds to allow formation of storms that may become hurricanes.

• Lifting

• Diverging

• Converging

• Geostrophic

• Converging

Which of the following are used as weather forecasting tools?

• AWIPS

• Doppler Radar

• Solar Sonographing

• MINTS

• Wind Profiles

• AWIPS

• Doppler Radar

• Wind Profiles

In the 1950s forecasting maps and charts were all plotted by hand

• True

• False

True

What chart uses the difference in height between two constant pressure surfaces where the higher thickness indicates warmer air?

• Constant pressure chart

• Thickness chart

• Width Chart

• Pressure gradient force

Thickness chart

What timeframe has the most accuracy and skill when forecasting weather

• 2-5 days

• 2 weeks

• 6-8 days

• 12-24hrs

• 12-24hrs

What is the reverse in Pacific equatorial current that causes global teleconnections

• Clima Tonto

• Semi Annual Fish Crisis

• Aqauatic shift

• El Nino, La Nina

• El Nino, La Nina

With Global warming being an issue what natural disaster would allow the earths surface to cool?

• Natural Methane Release

• Large Volcanic Eruptions

• Carbon Explosion

• Crop Dusting

• Large Volcanic Eruptions

What is considered to be the main cause of global warming

• Humans

• Increase in farm land

• Obliquity

• Deforestation

Humans

The average temperature of today is the lowest it has been in the last 1000 years

• True

• False

False

What are two consequences of global warming?

• Land Areas warm faster

• Less frequent heat waves

• Rise in sea level

• Drier winters/wetter summers

• Land Areas warm faster

• Rise in sea level

Global warming is a concern because it will melt the ice glaciers causing a net increase in land

• True

• False

False

When is air parcel unstable?

When the air parcel is warmer (less dense) than its surroundings, it rises. Instability occurs when environmental lapse rate > dry/moist adiabatic lapse rate.

Stages of an ordinary air mass storm

• Cumulus stage: Updrafts dominate.

• Mature stage: Updrafts + downdrafts, heavy precipitation.

• Dissipating stage: Downdrafts dominate; storm weakens.

What creates an overshooting top:

strong convection pushing updraft into the stable atmosphere

How does a shelf cloud form?

AKA Arcus cloud,

forms when warm, moist air rises along the forward edge of a gust front

What are squall lines, what type of weather do they bring

Long lines of severe thunderstorms bringing strong winds, heavy rain, and sometimes hail or tornadoes.

What are the different aspects of a squall line, and how does rear downdraft effect a storm

Rear downdraft strengthens surface winds, promotes forward tilt and organization; associated with bow echoes and derechos.

Types of lightning

–Forked lightening

–Heat lightening

–Sheet lightening

–Ribbon lightening

–Bead lightening

–Ball lightening

–Dry lightening

–St Elmo’s Fire

How does lightning form

Charge separation within cloud (ice collisions); electrons flow to ground or other cloud areas; rapid expansion of air causes thunder.

Define tornado def, rotation diameter, and lifespan

• Rotating column of air connected to a thunderstorm and ground

• Typically counterclockwise in Northern Hemisphere

• Diameter: 100–600 meters average

• Lifespan: ~5–10 minutes average (some last hours)

Lifecycle of tornado

1. Dust whirl

2. Mature

3. shrinking

4. decay

Best conditions for tornado

• Warm moist surface air

• Cold dry air aloft

• Strong wind shear and instability

• Often in spring with a dry line

Peak tornado season

Spring due to converging airmasses, summer has fewer but still possible

Strongest winds of a tornado where

South west, left side due to added wind motion and rotation

How are tornado winds measured

• Doppler radar (velocity scans)

• EF Scale (Enhanced Fujita), based on damage

• Post-storm surveys assess wind strength indirectly

Water spout composition

water droplets from ocean/lake surface

Tropics location and how are the seasons defined

23.5 N and S of equator, june 1st thru nov 30

Tropical wave and how it moves

tropical wave (aka eastely) moves off coast of africa toward west, seeds tropical cyclones

what do tropical wavbes become

tropical depressions, then storms, then hurricanes

eyewall characteristics

strongest winds, intense rainfall

Hurricane Season

Peak in June-Nov, peak sept

Upper-level winds & shear impact:

• Wind shear disrupts vertical structure and can weaken or prevent hurricane formation.

hurricane categories

Saffir-Simpson Scale (1–5), based on sustained wind speed

Hurricane watch vs warning

• Watch: Possible in 48 hours

• Warning: Expected within 36 hours

How does ocean water, atmospheric stability and windsheer effect hurricanes

warm ocean fuels hurricane, unstable air helps, low windshear keeps intact

Hurricane vs mid lat cyc

• Hurricane: Warm-core, no fronts, fueled by warm water

• Mid-latitude cyclone: Cold-core, has fronts, fueled by temperature contrast

What is storm surge

Coastal flooding from wind-driven ocean water pushed ashore, worsened by low pressure.

The three forecasting techniques

Numerical, ensemble, persistence

What does el nino bring

Warmer winters in northern US; wetter in the south; suppressed Atlantic hurricane activity

Forecast defs (climatolohical, persistence, analog)

• Climatological: Based on averages

• Persistence: Based on current trends

• Analog: Comparing to past similar patterns

External causes of climate change

• Volcanic eruptions, solar variability, human activity (GHGs), orbital changes

How albedo effects surface temps

Higher albedo = more reflection = cooler surface temps (e.g., snow reflects sunlight)

How volcano impact to cooling and how it carries through world

Ash blocks sunlight → temporary global cooling; carried globally by upper-level winds.

Climate models show what tyope of atmospheric activity

• Warming trends, altered precipitation, and more extreme weather with rising GHGs.

Eccentricity, precession, obliquity are part of what theory

milankovitch orbital cycles