Climate Change Exam 2
List and describe the two primary types of lightning, including which one is more common.
Intracloud and cloud-to-ground, intracloud is more common (80%)
Identify and describe freezing rain
Snow melts in warm layer. The cold layer below is too shallow and water freezes on contact with sub-freezing ground/objects
List the three characteristics of hurricanes that cause the most damage
Storm surge, flooding, and wind damage
Identify and describe precipitation growth processes associated with warm clouds
collision-coalescence
Given a figure or text description of an idealized vertical profile of environmental temperature, evaluate the most likely precipitation to reach the ground in a winter storm
*refer to picture on phone
Define and describe a blizzard
A snowstorm with winds of at least 35 mph, and visibility reduced to less than 1/4 mile with snow and blowing snow
What is the difference between a lightning stroke and a lightning flash?
A stroke is comprised of a leader (stepped or dart) and a resulting return stroke. A flash is a compilation of lightning strokes.
Describe how large scale wind circulations and pressure features can influence hurricane tracks
Bermuda High pressure can direct storm tracks, easterly trade wind regime
Identify and describe sleet
Snow melts in warm layer. Refreezes in the lower and deeper cold layer
Explain the basic idea behind the Saffir-Simpson scale for hurricanes. Identify and describe the relative difference between the typical storm surge and damage between a low category (1-2) and a high category (4-5) hurricane.
1. 74-95 mph (64-82 kt). Storm surge 4-5 ft 2. 96-110 mph (83-95 kt). Storm surge 6-8 ft 3. 111-129 mph (96-113 kt). Storm surge 9-12 ft 4. 130-156 mph (114-135 kt). Storm surge 13-18 ft 5. >157 mph (135 kt). Storm surge >18 ft
List three trigger mechanisms for hurricanes
1. Intertropical convergence zone 2. Easterly winds in trade wind flow 3. Cold fronts extending into tropics
List four environmental properties required for hurricane formation
1. Sea surface temperature has to be greater than 27 degrees Celsius 2. Deep layer of warm water 3. Weak wind shear 4. At least 5 degrees from the equator
Explain the difference between a dry thermal and a convective cloud
A convective cloud forms from pockets of warm air rising as thermals with invisible water vapor, and at the dew point temperature condensation creates the cloud base
Define a thunderstorm and a severe thunderstorm
A cumulonimbus cloud that produces lightning Severe: a) Hail > 1 inch diameter (¾ inch prior) b)Wind gust >50 kt (58 mph) c)Tornado
What are the hook echoes and vaults, and why are they important?
A hook echo is a small appendage attached to the main body of the storm on a radar image. Hooks are significant because their appearance usually means tornado formation is imminent. A vault is where the inflow of warm surface air enters a supercell. Air entering the vault rises and water vapor condenses to form a dense concentration of water droplets. On radar, the vault is typically found in the southeast quadrant, an area that appears "missing" on the radar image.
What two factors can ultimately stop rising parcels of air from continuing upward?
A layer of stable air can stop parcels, as well as entrainment, which is when unsaturated air is introduced into the parcel and causes some of the liquid droplets to evaporate and make the cloud less buoyant.
Explain how microbursts form and why they present a serious threat to aviation
A microburst is a localized downburst. They create strong wind shear upon reaching the surface. Planes flying into the microburst first encounter a strong headwind which provides lift. Pilots respond by turning the aircraft downward. After the plane passes through the core of the downdraft, the headwind disappears and is replaced by a tailwind which causes the plane to abruptly lose altitude and crash.
Define a tornado
A violently rotating column of air, pendant from a cumulonimbus cloud, in contact with the ground and nearly always observable as a 'funnel cloud"
What is the difference between a tornado watch and a tornado warning?
A watch is issues by the SPC and signifies that a part of the country appears vulnerable to impending severe storm activity. A warning alerts the public to the observation of an actual tornado or the detection of tornado precursors on Doppler radar.
Describe the situations that can cause air to be absolutely stable, absolutely unstable, or conditionally unstable.
Absolutely unstable: the rising air is cooling more slowly than its surroundings. Air will continue to rise if given an initial upwards push. Lifted parcel is warmer Absolutely stable: temperature of parcel cools more quickly than surrounding air, if lifted, it will sink back to its original location, it is heavy and negatively buoyant. Conditionally unstable: The ELR is between the dry and saturated lapse rates, the lifted parcel will either sink or rise depending on whether or not it becomes saturated.
What are riming and aggregation?
Aggregration is the joining of two or more ice crystals to form a single larger one called a snow aggregate. Riming is when an ice crystal falls through supercooled cloud water droplets, collides with them and the liquid water freezes on the ice crystal, allowing it to grow bigger
Explain how thunder forms in a lightning storm
Air expands explosively due to an increase in temperature during a lightning stroke
What causes thunder?
Air heated rapidly by a lightning stroke initiates a shock wave known as thunder.
How big are air mass thunderstorms and how long do they usually persist?
Air mass thunderstorms are typically highly localized but can grow to impressive heights, topping out at the tropopause. They typically hast only about an hour.
How are outflow boundaries formed, and what effect do they have?
An outflow is nothing more than a thunderstorm downdraft that spreads out after hitting the surface. They typically converge with warmer surrounding air to form an outflow boundary.
Describe the size, sea-level air pressure, and wind speed of a typical hurricane
Average diameters are approximately 600 km (350 mi) and central pressures average about 950 mb but may be as low as 870 mb. To be classified as a hurricane, a storm must have sustained winds of 120 km/hr (74 mph) or greater.
Why is the right-hand side of a hurricane the most dangerous?
Because wind speeds combine with the speed of the storm's movement to create the area of highest potential impact.
Identity and describe snow
Begins as snow and layer is cold enough to remain frozen
Identify and describe precipitation growth processes associated with cold clouds
Bergeron process, riming, aggregation
What is the highest hurricane category on the Saffir-Simpson scale? How frequently do hurricanes of that magnitude occur?
Category 5 hurricanes are the strongest storms on the Saffir-Simpson scale. These are very rare events as only two category five storms made landfall within the US since 1900.
Identify the location along a bow echo squall line where the strongest straight line winds and tornadoes would be likely.
Center of the bow echo is where the strongest winds are
Define vertical wind shear
Change in wind speed and/or direction with height
How common is cloud-to-ground lightning relative to cloud-to-cloud lightning?
Cloud-to-cloud lightning is much more common than cloud-to-ground lightning, with about 80% of lightning happening in-cloud, and only 20% happening between clouds and Earth.
Describe the geographic distribution of hurricanes, typhoons, and cyclones. What environmental conditions favor the development of such storms?
Collectively, all the above names refer to tropical cyclones. As the name implies, tropical cyclones originate within low latitude, "tropical" regions. The storms typically form in association with rapid convection associated with the ITCZ. Tropical cyclones traverse east to west, carried in the global north-or south-east trade winds as they move toward higher latitudes. The storms feed off of massive amounts of latent heat of condensation such that warm tropical waters, and associated evaporation, are required. The storms develop best towards the western edges of the ocean basins where the depth of the marine layer is most extensive. The western North Pacific sees the highest frequency of tropical cyclones, while the South Atlantic produces none. (Hurricanes: Atlantic and Eastern Pacific Ocean, Typhoons: Western Pacific, Cyclones: Indian Ocean)
List a typical size of cloud and precipitation particles
Condensation nuclei are around 0.1 micrometers, cloud droplets are about 10 micrometers, rain drops are about 1000 micrometers/1 millimeter
Define and describe condensation and condensation nuclei
Condensation: water vapor to liquid Condensation Nuclei: Small (~ 0.1 micrometers) aerosols that act as "seeds" for growing cloud droplets
Define a tropical cyclone
Cyclonically rotating warm-core disturbance with a mean surface wind greater than 25 knots
Define a derecho and explain its significance relative to high-impact convective weather
Derecho is a widespread, long-lived, straight-line wind storm that is associated with a land-based, fast-moving group of severe thunderstorms like bow echoes. Derechos can cause hurricane-force winds, tornadoes, heavy rains, and flash floods.
Explain how bow echo storms have strong straight-line winds
Derecho is a widespread, long-lived, straight-line wind storm that is associated with a land-based, fast-moving group of severe thunderstorms like bow echoes. Derechos can cause hurricane-force winds, tornadoes, heavy rains, and flash floods. Small.
Identify and describe the three stages of the life-cycle of a single-cell thunderstorm. Explain why a single-cell storm has a relatively short life span
Developing/cumulus stage: New updraft Mature stage: Both updraft and downdraft Dissipating stage: Dominated by downdraft Downdraft collapses on updraft, cutting off energy source and ensuring a short life
Identify the radar technology that allows the measurement of the direction of motion of precipitation.
Doppler. Inbound: negative and cool colors. Outbound: positive and warm colors
Identify and describe the difference between freezing rain and freezing drizzle
Drizzle is light precipitation (small drops in the form of drizzle, 0.2 mm in diameter) that freezes on surfaces and causes an ice glaze Rain is bigger
Identify the appropriate lapse rate associated with a dry thermal and a convective cloud.
Dry thermal: 9.8 °C/km
Identify and describe the environmental lapse rate, dry adiabatic lapse rate and saturated adiabatic lapse rate
Environmental: actual temperature as measured by a radiosonde (weather balloon) Dry: Unsaturated parcel of air = 10°C per km Saturated: Saturated (wet) parcel of air = 6°C per km.
Define supercooled water drops and describe their relationship to drop size
Existence of water (drops) in a liquid state at T < 0 degrees C. Supercooled water is more likely for small drops
List and describe the four key components of hurricane structure (eye, eye-wall, inner rainband, outer rainband).
Eye: center, warm core Eye-Wall: powerful winds, high pressure Inner Rainband: Outer Rainband:
Identify what time of the year hurricanes are most likely in the Atlantic basin.
Fall, August to September
When are hurricanes most likely to form?
Fall, August-September. During the warm season. In the northern hemisphere the "hurricane season" extends from June 1 to November 30.
Describe the sequence by which electrical imbalances lead to lightning strokes
For cloud-to-ground lighting to occur, a stepped-leader must emanate from the cloud base. This ionized particle chamber forks repeatedly from a central chamber. Each section, occurring over a single microsecond, traverses about 50 m in length. When contact is made with an unlike charged region, electrons flow through the chamber resulting in an illuminated return stroke. Air in the ionized chamber is rapidly heated producing a shock wave (thunder). Typically, multiple strokes are needed to neutralize the charge imbalances.
Describe the current theories regarding the formation of charge separation
For lightning to strike, electrical charges must separate in different portions of a cloud. Positive charges migrate to upper regions of the cloud while negative charges accumulate in lower areas. Two theories account for this charge separation. The first, the thermoelectric effect, is believed to involve ice crystals. Lighter positively charged crystals rise to higher areas of the cloud while heavier, negatively charged crystals fall to lower areas. Induction is the second theory concerning charge separation. Induction involves opposite charges attracting. The top of falling ice pellets will be negatively charged due to the positive charge of the upper atmosphere. Finer ice crystals or small drops, acquiring a positive charge, move to the upper cloud area while the heavier pellets stabilize in the lower cloud areas.
Describe how free convection and a dry thermal forms
Free Convection: Ground heated by radiation Dry Thermal: Air in contact with warmest ground is warmer and therefore less dense than surrounding air. Rising and cooling air.
Identify and describe the difference between freezing rain and sleet
Freezing rain goes through a shallow layer of cool air and becomes supercooled, freezing on contact with the surface or something on the surface. Sleet goes through a dense layer of cool air and refreezes before it hits the ground.
Identify and describe rain
Grows in warm portion of cloud or snow from cold cloud melts in warm layer below
Define the gust front and explain its role in the evolution and propagation of multi-cell thunderstorms
Gust front is boundary between rain cooled, stable air and warm, unstable air. New cell develops due to lifting at gust front of older cell and unstable air. Process repeats over-and-over to maintain multicell.
Evaluate the likely approximate location of a potential tornado in a supercell, if given a figure depiction or text description of one or more radar and/or visual storm features.
Hook echo or near/within the wall cloud
What ocean surface characteristics are required for the intensification of storms into hurricanes and the maintenance of hurricanes?
Hurricanes form only over deep water layers with surface temperatures in excess of 27oC (81oF) as hurricane energy is derived from latent heat release and associated evaporation of water.
Define ice nuclei and explain its role in precipitation growth processes
IN are aerosol particles that activate (initiate) freezing, required to freeze supercooled drops. Grows through riming.
Explain how the static stability condition (i.e., whether an air parcel is absolutely stable, conditionally unstable or absolutely unstable) can be determined by comparing the environmental lapse rate with the dry adiabatic lapse rate and/or saturated adiabatic lapse rate
If the environmental lapse rate (ELR) exceeds the dry adiabatic lapse rate (DALR), the air is absolutely unstable. If the environmental lapse rate (ELR) is less than the saturated adiabatic lapse rate (SALR), the air is absolutely stable. the environmental lapse rate (ELR) is between the dry adiabatic lapse rate (DALR) and the saturated adiabatic lapse rate (SALR).
Explain how buoyancy affects the air's susceptibility to uplift
If the parcel is warmer than its surroundings, it will be less dense and more buoyant, thereby experiencing a lifting force. If the parcel is colder than its surroundings, it will be more dense and have a negative buoyancy, thereby experiencing sinking.
Describe the process of tornado formation from supercell storms
In a supercell, the first step of tornado production is the slow, horizontal rotation of a large segment of cloud. Rotation begins deep within the cloud interior several kilometers above the surface. These mesocyclones often preceded a tornado by as much as 30 minutes. Mesocyclones depend on strong wind shear which results as winds shift from southerly to westerly with altitude along with an increase in speed. Strong updrafts in the storm tilt the horizontally rotating air so that the axis of rotation becomes vertical. Intensification of the mesocyclone requires a decrease in rotational area which leads to an increase in wind speed. The narrowing column of rotating air stretches downward and a portion of the cloud base protrudes downward to form a wall cloud. A funnel cloud forms when a narrow, rapidly rotating vortex emerges from the base of the wall cloud. If the funnel cloud touches the surface, a tornado has officially occurred.
Where are tornadoes most likely to be embedded in a hurricane?
In the right-front quadrant due to frictional drag of lower atmospheric winds upon landfall.
How do the growth processes of droplets in warm and cold clouds differ?
In warm clouds, droplets grow by the collision-coalescence process. in cold clouds, droplets grow through the Bergeron Process, riming, and aggregation.
Evaluate relatively safe and relatively unsafe locations for a person to be when there is lightning nearby.
Indoors or metal-topped vehicle is best. Do not stand under a tree or other tall object that might serve as a lightning rod. Avoid open areas. Avoid standing on rooftops, hills, or other high areas. Do not watch lightning storms from a pool, lake, or hot tub
Explain how strong wind shear can increase the longevity and severity of storms
It can tilt the storm so that downdraft doesn't interfere with the updraft, allowing for the storm to last longer
What will determine whether air that is conditionally unstable will become buoyant?
It must be saturated and lifted to a critical altitude called the level of free convection to become buoyant
Define and describe a single cell-thunderstorm, including its typical life span and size
Life span of about 20 to 30 minutes. Small, less than 10 km
Define and describe a lake-effect snowstorm, including the two key requirements for one to occur
Localized mesoscale systems produced by the vertical transfer of heat and moisture from the warmer lake surface to the very cold air above. Cold arctic air + warm lake water.
Identify and describe the key similarities and differences between single-cell and multi-cell thunderstorms
Multicell thunderstorms are made up of a group of single-cell storms, so, everything is similar except the stronger vertical wind shear, and the fact that it has multiple storms in one. Gust front propagates more storms in a multicell
Identify global hotspots for lightning in the United States and around the globe
Near the equator, especially in central Africa
Identify favored regions around the globe where hurricanes form
Northern hemisphere, largest and most intense storms in the Western Pacific, seldom poleward of 25 degrees.
Identify and describe orographic lift
Occurs when a mass of air is deflected over or around a terrain, usually a hill or a mountain.
Identify and describe localized convection
Occurs when differential heating at the surface causes air to lift. The air expands and cools as it lifts, causing condensation and cloud development
Identify and describe surface convergence
Occurs when there is a horizontal movement of air into a region. Convergence often occurs at surface low pressure. When air converges along the Earth's surface, it is forced to rise since it cannot go downward.
Identify and describe frontal lift
Occurs when two air masses converge at the front
Describe the four mechanisms that lift air and promote cloud formation
Orographic Uplift: hills and terrain Frontal Lifting: airflow along frontal boundaries, gentle slopes, warm air forced upwards Surface Convergence: Occurs when there is a horizontal movement of air into a region. Convergence often occurs at surface low pressure. When air converges along the Earth's surface, it is forced to rise since it cannot go downward. Adiabatic cooling and cloud development Localized Convection: Occurs when differential heating at the surface causes air to lift. The air expands and cools as it lifts, causing condensation and cloud development. Arises from buoyancy, the tendency for a lighter (less dense) fluid to float upward through a denser one
Describe the concept of an air parcel and explain what an adiabatic process is
Parcel of air expands and expands and contracts freely. Remains as a single unit. No heat exchange with the outside air the outside air (Adiabatic Process) Adiabatic Process: Parcel expands when lifted due to when lifted due to lessening pressure. Molecular action slows = cools at a steady rate. Compresses when forced down = Warms at a steady rate.
Identify the radar technology that allows the detection of precipitation type
Polarimetric Radar
Identify and describe the difference between steady rain and rain showers
Rain showers are precipitation events associated with convective activity like thunderstorms Rain is associated with warm clouds and when surface temperatures are above freezing
Define lapse rate
Rate of cooling (or warming) of the atmosphere with height
Explain how a thunderstorm separates electrical charge needed for a lightning flash
Rebounding collisions between graupel and ice crystals. Positive charges accumulate at top of cloud on ice crystals, and negative charges in the middle part of cloud on graupel.
Explain why some thunderstorms have short lifespans and yield little damage and others are able to develop into severe thunderstorms
Self-extinguishing thunderstorms largely describe air mass thunderstorms. These storms are spatially and temporally limited. Their life cycles are comprised of a cumulus stage, marked by updrafts, a mature stage, delineated by both up- and downdrafts, and a dissipative stage, characterized by downdrafts. The latter stage is caused by the prevalence of precipitation-initiated downdrafts which effectively cut off in-rushing updrafts. As the updrafts carry water vapor needed to sustain the storm, the storm rapidly dissipates. Severe thunderstorms occur when thunderstorms reach extraordinary proportions with regard to wind, precipitation, and/or produce tornadoes. Such storms are self-propagating and typically occur in groups. The group configuration allows unusual circulation features which support individual thunderstorms thereby increasing their spatial and temporal extent. Groups of severe thunderstorms include Mesoscale Convective Complexes (MCCs), and Squall Lines. Individual Supercell thunderstorms may also occur. These storms are isolated storms which interact with environmental conditions to increase their longevity and size. Atmospheric conditions important to virtually all severe thunderstorms include: wind shear, high water vapor content through the lower troposphere, a forcing (lifting) mechanism, and potential instability.
it is never too cold for snow to occur, is that also true of sleet?
Since sleet needs a layer of cold air to refreeze, it cannot be too cold for sleet.
Identify where snowfall is most likely to occur relative to the synoptic structure of a midlatitude cyclone
Snow farthest, then ice pellets, freezing rain, and rain. Behind the warm front is a line of showers or thunderstorms.
Identify and describe the type of vertical wind shear required for severe storms, including multi-cell and supercell storms
Strong vertical wind shear
Identify the additional fourth ingredient needed for severe thunderstorms
Strong vertical wind shear
Identify which storm types are most likely to be severe (e.g., single-cell, multi-cell, supercell)
Supercell most likely, then multicell, then maybe single-cell
Describe the processes that lead to tornado development in supercell and non-supercell storms.
Supercell tornadoes begin with mesocyclone development in the presence of vertical wind shear. Winds shift from southerly to westerly with height and strong updrafts tilt he rotation region to a vertical position. The diameter of the rotating column decreases, initiating an increase in wind speed through the conservation of angular momentum. The rotating air column penetrates the cloud base producing a wall cloud. From this, a narrow rotation region, the funnel, emerges and continues to the surface. Nonsupercell tornadoes initiate from the interaction of outflow boundaries between two or more thunderstorms. They may also generate from strong convection along a convergence zone.
Identify the type and relatively frequency of severe weather in single cell thunderstorms, multi-cell thunderstorms and supercells
Supercells are frequent producers of severe weather including large hail, strong winds, tornadoes, and heavy rain
Identify and describe tornado alley. Describe where significant tornadoes are most likely to occur in the United States.
Texas/Central Plains United States. Also likely to occur in the Southeast
Describe the enhanced Fujita scale for classifying tornadoes. Which category is most common? What is the highest EF-value that can actually occur in nature?
The Fujita scale is a scale from 0 to 5 with a category 5 being the strongest tornado possible. In the US, 69% of all tornadoes are classified as being weak (F0-F1), 29% are strong (F2-F3) and only 2% are violent (F4-F5).
What are the three stages of an air mass thunderstorm?
The cumulus stage, which is marked by all updrafts, feeding the storm and causing rapid growth. The mature phase which is marked by both up- and downdrafts, and related precipitation. And the dissipation phase, which is marked by all downdrafts.
Explain why the saturated adiabatic lapse rate is always less than the dry adiabatic lapse rate
The heat released from the condensation process reduces the saturated adiabatic lapse rate
Define and describe the hook echo and weak echo region radar reflectivity features in supercells. Explain their significance.
The low-level mesocyclone is located within the notch of the hook echo in radar reflectivity. If present, a supercell tornado is often in or near the hook echo and mesocyclone features in radar reflectivity and Doppler velocity, respectively. WER is a radar indication of the intense updraft in supercell lofting precipitation upward, causing a "weak echo region" in radar reflectivity
Why is the term heat lightning misleading?
The term implies that there is something unusual about heat lightning. However, it is just distant lightning. Because of the distance, no thunder is heard.
What are wall clouds, and why is their appearance a cause for concern?
The narrowing of the mesocyclone causes air to stretch downward with a portion of the cloud base protruding downward. This is the wall cloud. It indicates mesocyclone strengthening and the likelihood of tornado development.
Describe the eyewall replacement cycle process and explain its significance to hurricane evolution and intensity
The outer eyewall blocks warm, unstable air from spiraling into the inner eyewall. Thunderstorms in the inner eyewall no longer have a source of instability for their updrafts, so the inner eyewall collapses - This signals a temporary weakening phase. (6-18hrs). Outer eyewall (now the primary eyewall) contracts (shrinks). This signals the rapid intensification phase of the eyewall replacement cycle. Wind speeds typically increase by 15mph to 40mph due to conservation of angular momentum. (Keeps hurricane alive)
Identify and describe the processes of lightning formation
The rapid and staggered advance of a shaft of negatively charged air is called a stepped leader. As the leader approaches the ground a spark is created. When the leader and the spark connect a flow of electrons illuminates the cloud by strokes, or return strokes. Not all of the first stroke neutralizes the negatively charged ions and results in another leader, the dart leader, in 1/10 of a second. The combination of multiple strokes is called a lightning flash.
Describe the location and timing of tornadoes in North America
The regular mixing of vastly different air masses in the central US leads to a global high frequency of these phenomena. The absence of topographic barriers and the presence of the warm Gulf of Mexico allow for regular and repeated incursions of cold, dry air-streaming equatorward to mix with warm, moist air flowing poleward. The Great Plains, therefore, sees the highest frequency of tornadoes with Texas being the state with highest tornado numbers. May is the time of greatest overall frequencies followed closely by June.
What feature associated with hurricanes causes the greatest destruction to coastal regions? Is this also true of land regions?
The storm surge is responsible for a large percentage of damage along coastal regions. Storm surges occur as water piles due to heavy winds and low atmospheric pressure and increase with storm intensity. Inland regions see most damage from high winds, heavy rainfall, and occasional tornadoes.
Explain the role of location relative to the eye of the hurricane, tides and shape of coastlines play in wind, flooding and storm surge damage
To the right, damage in all three is more intensive
List and describe two important elements of hurricane forecasting
Track and Intensity
Explain the basics behind how weather radar works, including microwave transmission and back-scattering by clouds and precipitation.
Transmits and receives pulses of microwave radiation. Transmits very short pulses of radiation, listens for returned energy (echoes). Transmitted energy is scattered by objects on ground and in atmosphere
Describe the cloud and precipitation patterns associated with hurricanes, including those associated with the eye and eye wall
Tropical cyclones usually consist of a central eye surrounded by large cumulonimbus thunderstorms that comprise the eye wall. The eye is the area of lowest pressure and it is about 25 km in diameter on average. Within the eye, winds are relatively calm and descending. Thus, few clouds, if any, exist. The eye wall is the area of greatest winds and precipitation as this is where the greatest uplift of air and largest thunderstorms occur. Extending outward from the eye are swirling cloud bands of cumulonimbus thunderstorms. Weak uplift and low precipitation regions separate these bands.
Describe the characteristics that distinguish tropical disturbances, tropical depressions, tropical storms, and hurricanes from one another
Tropical disturbances are essentially clusters of thunderstorms. When a disturbance has at least one closed isobar it is upgraded to a depression. Upon further intensification to wind speeds of 60 km/hr (37 mph) the storm is officially classified as a tropical storm. Hurricane status is gained when winds reach or exceed 120 km/hr (74 mph).
List typical values for the dry and saturated adiabatic lapse rates
Typical dry adiabatic lapse rate: 10 degrees C/km Typical saturated adiabatic lapse rate: 6 degrees C/km
Describe the relative relationship between the temperature of an air parcel (Tparcel) and the temperature of the environmental air (Tair) for unstable, stable and neutral static stability conditions
Unstable: temperature of parcel is warmer than surrounding air Stable: temperature of parcel is colder than surrounding air Neutral: temperature of parcel is equal to that of surrounding air
Describe the characteristics that distinguish warm, cool, and cold clouds
Warm clouds are clouds in the tropics that have temperatures above 0 degrees Celsius throughout. Cool clouds are clouds that have temperatures above 0 degrees Celsius in the lower reaches of the cloud, and subfreezing temperatures in the upper reaches of the cloud. Cold clouds are clouds that have temperatures below 0 degrees Celsius throughout the cloud and consist entirely of ice crystals and supercooled droplets. they are typically in the midlatitude.
Identify the three key ingredients required for thunderstorm initiation
Water vapor, Instability, Lifting mechanism
Identify and describe some distinctive features of supercells in radar reflectivity, Doppler radar velocity and visual storm structure.
When viewed with Doppler velocity imagery a typical mesocyclone appears as a cyclonic circulation ~2-10 km in diameter with values of the toward-and-away velocity couplet on the order of 25 to 75 m/s.
Is there a "typical" path that hurricanes take after forming?
Yes, a parabolic one. Once storms gain latitude, they recurve toward the northeast through the influence of surface and upper level westerlies. They don't always follow this path, however.
Define the Atlantic Multidecadal Oscillation (AMO) and explain its influence on hurricane intensity.
a 25-40 year oscillation in water temperatures and is a major factor in the increase in Atlantic hurricane activity. Warmer water = more/more intense hurricanes
Define a micro-burst and explain why it is a significant potential aviation hazard for planes at airports during landing (or takeoff)
a localized column of sinking air (downdraft) within a thunderstorm and is usually less than or equal to 2.5 miles (4 km) in diameter. It can cause extensive damage at the surface, and in some instances, can be life-threatening.
Define vorticity.
a measure of rotation
Define a flash flood and identify some factors that can enhance its intensity and impact.
a sudden local flood, typically due to heavy rain, often from multicell thunderstorms. Enhanced by prolonged rain, saturated soils, urbanization, and/or terrain.
Identify and describe the wall cloud in a supercell. Explain its significance
a visual manifestation of a lowered cloud base associated with a rotating supercell updraft. Importance: Most significant supercell tornadoes are within or near the wall cloud
Describe the following types of storm systems: a. mesoscale convective systems b. squall lines c. mesoscale convective complexes d. supercells
a. Mesoscale convective systems - These are groups of thunderstorms which interact with each other. There are two general types, MCSs that are also called squall lines, and MCCs. b. Squall lines - Linear bands of thunderstorms typically ahead of a cold front in a mid-latitude cyclone are MCSs called squall lines. c. Mesoscale convective complexes - Oval or roughly circular clusters of thunderstorms are MCCs. Individual cells are part of a single system. d. Supercells - These are intense powerful storms that contain a single updraft. They can be isolated or as a part of an MCS.
Define static stability, including the three types (unstable, stable, and neutral)
air's susceptibility to uplift -Unstable: Air will continue to rise if given an initial upwards push. -Stable: Air will resist the upward push and sinks back to the original level. -Neutral: Air will not rise or sink. If displaced, it will rest at the height to which it was displaced.
How do lakes enhance precipitation downwind?
called lake-effect and lake-enhanced precipitation, occurs when lake water warms and evaporates moisture into the lower atmosphere, the air becomes unstable, temperature lapse rate increases. Enhances precipitation downwind because moisture is swept downwind when the storm passes over the lake.
Define and describe collision coalescence
causes precipitation in warm clouds. Collision-coalescence begins with large drops, called collector drops, which fall faster than smaller droplets. As the collector drops fall, they overtake smaller droplets in their path and provides the opportunity for collisions and coalescence. Basically, the bigger collector drop overtakes the smaller droplets, collide with them, absorb them and grow larger yet
Define and describe riming
ice crystal falls through supercooled cloud water droplets, collides with them and the liquid water freezes on the ice crystal, allowing it to grow bigger
How do collision and coalescence increase the size of cloud droplets?
increases the size of droplets by having a larger collector drop collide with smaller droplets in its path. If the drops below the collector drop are too small, they'll get swept aside by the wind and have a lower likelihood of colliding with the larger drop. If the collector drop and a smaller drop do collide, they can either combine to form a single droplet (coalescence) or bounce apart. In most cases, the droplets stick together and grow larger.
Explain the relationship between the supercell updraft and mesocyclone.
mesocyclone is the rotating vortex extending upwards due to the updraft
Explain why the formation of sleet requires an inversion
needs to refreeze before it hits the ground, begins as an ice crystal, encounters warm air and melts into a raindrop, encounters another layer of cold air in order to freeze again. Without the second cold layer inversion, the precipitation would reach the ground as freezing rain.
Identify and describe the role of the Storm Prediction Center (SPC) in forecasting severe weather.
puts out convective outlooks. Thunderstorms (no severe), Marginal (isolated severe), Slight (scattered severe), Enhanced (numerous severe), Moderate (widespread severe likely), High (widespread severe expected)
Define a supercell thunderstorm and mesocyclone
storms with long-lived cores and rotating updrafts. A mesocyclone is a rotating vortex in conjunction with the updraft in a supercell storm.
Explain where the vorticity for mesocyclones in supercells comes from
strong updraft
Bow echo
the characteristic radar return from a mesoscale convective system that is shaped like an archer's bow. These systems can produce severe straight-line winds and occasionally tornadoes, causing major damage.
Define and describe aggregation
the joining of two or more ice crystals to form a single larger one called a snow aggregate
Define and describe deposition
water vapor turning into ice
Define and describe a snow drift
when the wind blows snow and deposits it into mounds
Identify and describe the relative difference between a tropical disturbance, tropical depression, tropical storm and hurricane
wind < 20 kts (23 mph) Tropical disturbance 20 kts ≤ wind < 34 kts (39 mph) Tropical depression 34 kts ≤ wind < 64 kts (74 mph) Tropical storm 64 kts ≤ wind Hurricane
