Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
82 Cards in this Set
- Front
- Back
|
Weather/precipitation modification |
seeding of clouds for enhancement of precipitation |
|
|
Fog dispersal |
Main reason to have is for aviation operations Only success has been in colder weather when you have freezing temps |
|
|
Hail suppression |
Russian scientists have claimed success Not looked at by scientists |
|
|
Fronts blank air masses |
Separate |
|
|
Cyclone |
Generalized name given to areas of low pressure Tornado Hurricane |
|
|
Mid latitude frontal cyclone |
Extra tropical cyclone Cold core low Rare for frontal cyclones to become huricanes going from extratropical to tropical is rare tropicals will become extratropical |
|
|
Occluded front |
when a cold front overtakes a warm front |
|
|
Fronts |
Boundary between 2 air masses |
|
|
Frontolysis |
Dying out front |
|
|
Frontogenesis |
Front is beginning in an area |
|
|
Overrunning |
moisture that is overrunning the colder air |
|
|
4 types of fronts |
1. Cold front 2. Warm front 3. Stationary front 4. Occluded front |
|
|
Cold front |
colder air actively adv into a region formerly occupied by warmer air; Always drawn in blue Depicted only on a surface map Triangle points into dir front is moving Thunderstorms and hail; most severe weather Perpendicular to air flow Steep slope (1:50) |
|
|
Warm Front |
When the surface position of a front moves such that warmer air occupies territory formerly occupied by colder air More gentle slope (1:150) Red line with semi circle Only on surface level map perpendicular to air flow |
|
|
Stationary front |
Little forward movement of either air mass Usually upper level wind are parallel to the surface front boundary depicted by red semicircle and blue triangle Depends on the upper level conditions |
|
|
Occluded front |
Cold front that overtakes a warm front in the vicinity of a surface low very rare that we see this in TX, more common in N US Purple and semi circle triangle |
|
|
Dry line |
not a front but is a barrier b/w fronts
Boundary b/w cT(hot dry air) and mT(warm moist air) Found most commonly over the US plains states (Tx northwards) cT air mass orig over deserts of SW US & N Mexico Molecular weight of cT air is heavier than that of the mT air so when this feature moves eastward dry line scale lift occurs and thunderstorms can occur |
|
|
What is weather forecasting |
Predicting how the state of the atm will change w/ time To be able to forecast the weather, current weather info over a large area must be known The process of forecasting the weather is like putting a puzzle together |
|
|
Geostationary satellites |
As the earth rotates, satellites rotate w/ Earth and view the same spot |
|
|
GOES (EAST) |
Dir over equator at 75 deg W lat |
|
|
GOES (WEST) |
Dir over equator at 135 W long New Zealand, Australia all the way to the Rocky's E Pars of Asia to US |
|
|
Geostationary Satellite Imagery |
Visible Imagery Infrared Imagery Water Vapor Imagery |
|
|
Visible Imagery |
Monochrome View; Depends on the light of the sun; only ava when sun is overhead on your part of globe
|
|
|
Infrared Imagery |
Cloud top temp meas; the hotter the colors, the colder the temp; Red=cold |
|
|
Water Vapor Imagery |
Most imp in detecting mid to high atm water vapor; allows us to see where there is moist in the atm |
|
|
Radar Data |
Radars show the reflectivity from the rain drops Larger the droplet, the more reflectivity and color there will be in the radar data |
|
|
Velocity Data |
Radars show the reflectivity from the rain drops Larger the droplet, the more refl and color there will be in the radar data |
|
|
Dopolar radar |
Tells you the shape of the obj Most recent type of radar |
|
|
Radar Rules |
Cone of silence d/n rotate directly up W/ range from radar there is height Modes Clear Air Vs Precipitation Greens are inbound towards the radar Reds are out bound away from the radar |
|
|
Surface Weather Observation |
Taken at thousands of locations around the world on an hrly bases(airports, military bases, ships) Observations: automated, automated w/ manual augmentations; manual |
|
|
NWS Cooperative Climate Data |
Ppl give data on the highs and lows Not very tech adv Rain gauge therm |
|
|
World Mete Org |
Resp for the international exchange of weather and certifies that the observation process d/n very b/w nations since all weather obs must be comparable |
|
|
Where do most ppl get their weather forecasts |
Radio, tv, internat, newspapers AMS/NWA Radio/TV seal of approval programs |
|
|
AMS certified Broadcast Meteorologists |
These are voluntary professional orgs No licensing of mete, so the use seals |
|
|
Weather Watches |
Atm cond are favorable for the type of weather specified (generally larger geog area, longer time span: 4-6 up to 24-48 hrs) Only issued by National Weather Service |
|
|
Weather Advisory |
Type of weather specified is imminent or is occurring and is occurring and is a public inconvenience (smaller to larger geog area; generally in effect for 6-24 hrs) |
|
|
Weather warning |
Type of weather specified is imminent or occurring and an immediate threat to life and or prop (smaller geog area; smaller time period 1/2-1 hr) |
|
|
Weather forecast tools: Computes |
Numerical Weather Predictions (NWP) |
|
|
Numerical Weather Predictions (NWP) |
Computer atm "models" (programs) Models are mathematical in nature, data in data out Models are initialized and run generally one to four times a day |
|
|
Problems with NWP |
If bad in, bad out Models make certain assumptions and therefore have certain biases Data sparse areas of the World C/N adequately interpret many of the factors that influence surface weather Small disturbances/ small error tend to be amplified (chaos) esp w/ time |
|
|
Methods of forecasting |
Persistence Forecasting (in short term) Steady state/trend forecasting Ensemble forecasting Climatological forecasting Probability forecasting |
|
|
Persistence Forecasting (in short term) |
prob of most value in short term; loses value when weather is changing rapidly |
|
|
Steady state/ trend forecasting |
Look at what weather is doing in one place and calc dist to another city to know what will happen in that city, how fast sys moving |
|
|
Analogue Method forecasting |
Comparing sys thats happening to similar past sys |
|
|
Ensemble forecasting |
By product of NWP |
|
|
Climatological forecasting |
Most use in climates where the weather is stable |
|
|
Probability forecasting |
Very misunderstood fact of forecasting Forecaster certainty x areal coverage expected Ex 50%x20% = 1000 or 10.00% Point prob expression |
|
|
Accuracy inWeather Forecasting |
Accuracy rates in short term = 55-90%
Short term forecasts (today-tonight) 85-90% Medium term forecasts (2-3 days) 80-85% Larger range forecasting (4-8 days) 70-80% |
|
|
Ingredients for thunderstorm |
1. Atmospheric instability 2. Moisture (mT airmasses) 3. Atmospheric lift Most common in warmer equatorial climates |
|
|
Types of thunderstorms |
1. Single cell 2. Multicell clusters 3. Multicell lines 4. Supercenters |
|
|
Single cell thunderstorms |
Last 1-1.5 hrs Updraft Downdraft |
|
|
Multicell cluster thuderstorm |
Can cover states |
|
|
Multicell lines |
Lines of storms |
|
|
Supercenter |
Extreme thunderstorm Dangerous Produce tornados |
|
|
Stages of thunderstorm |
1. Cumulus: updraft dominated, clouds build higher 2. Mature: updraft/downdrafts coexist; air gets cold and heavy, precipitation falls; lightning 3. Dissipating: downdraft dominated; Cold air dominates, air sinks and cuts off updrafts, fuzzy clouds b/c breaking down |
|
|
Severe thunderstorm |
Hail >= 1" in diameter winds of 50 knots/58 mph or higher presence of tornado |
|
|
Difference in the structure of non-severe vs severe thunderstorms |
non severe have weak upper air wind severe have strong upper air wind |
|
|
Both severe and non severe thunderstorms have |
dangerous lighting |
|
|
Mesoscale Convective Systems (MCSs) |
Other thunderstorm phenomena Complex sys that form near fronts |
|
|
Mesoscale convective complexes (MCCs) |
other thunderstorm phenomena Special type og MCS Long lived, nocturnal formation |
|
|
Square line |
Line of storms, better org than general multicell clusters |
|
|
Bow echoes |
produce strong winds |
|
|
Mesocyclones |
strongly rotating updraft most d/n produce tornados |
|
|
Derechos |
Widespread convection/ thunderstorm windstorm downdraft Divergent |
|
|
Downbursts (Microbursts and macrobursts) |
footprint of the downdraft Microburst: 2.5 miles or less in diameter Macroburst: > 2.5 miles in diameter |
|
|
Straight line winds |
Downdraft that diverges when it hits the ground more common than tornadoes most damages from thunderstorms are caused by this Diverge |
|
|
Quarter sized hail |
Severe 1 inch 50 mph |
|
|
Baseball size |
2.75 inches 85 mph |
|
|
DVD/CD size |
5 inches 125 mph Can kill you |
|
|
Lightning |
Forms as result of separation of charges b/c of presence of ice crystals and cloud droplets in the strong updrafts and downdrafts begins at very end of cumulus stage into mature stage Bolt of lighting is about the diameter of pencil temp is 5 times the temp of outer surface of sun 54,000 F Can strike up to 10-20 miles away from the thunderstorm; 5 sec = 1 mile away Positive(more deadly) neg(less deadly) charges Positive at ground and upper storm; neg at cloud base Florida= lightning capital of US |
|
|
Heat lightning |
Heat d/n cause lightning if you can't hear thunder then heat lightning Not at risk |
|
|
Sheet lightning |
Result of rain concealing bolt but you see the whole base of the cloud |
|
|
Ball lightning |
lightning hits power lines; balls of fire travel down lines |
|
|
Avg thunderstorm days in Austin |
40-45 days |
|
|
Hail |
dependent on updraft and downdraft speed Largest hail falls NE of tornado In US hail occurs most freq central and S plains W/NW of Rockies Resp for home and agricult damage Largest hail in US history = 7 inch in diameter |
|
|
Tornado |
Converge Violently rotating column of air extending from base of cumulonimbus cloud Reach earth surface |
|
|
Flash floods |
#2 killer types of flooding 1. River flooding 2. Flash flooding: very quick S central TX flash flood capital of US 1. Subsoil limestone layers 2. Urbanization 3. Hilly nature of Texas Hill Country |
|
|
Summer heat |
Number one killer in the US Sign of heat stroke: we stop sweating Evaporative cooling depends on the amount of envir moist present |
|
|
Winter cold |
Hypothermia and frostbite |
|
|
Funnel cloud |
like a tornado but d/n touch the ground |
|
|
Ingredients for a tornado |
1. mT air masses(warm, moist air) 2. Extremely unstable air mass 3. Strong lifting mechanism 4. Initial temp inversion: explosively releases thunderstorm |
|
|
Climatology of tornado |
1. < 1% of all thunderstorms produce tornado 2. Atm pressure in the strongest tornadoes is thought to be about 10% less than std pressure 3. 1300 tornados, 80% weak, 19% strong, 1% violent |
