ATOC 1050 Midterm #3 with Melissa Nigro
Chapters 8, 9, 10, 11
This review guide has all of the info you’ll need to be ready for the test! There is a lot of memorization to do for this test and all of the definitions are here. There are definitions from the book, online sources, as well as videos, which will help you
understand concepts. Good luck on the last midterm and have a great Thanksgiving break. ☺
• Polar-front theory – a working model of how a mid-latitude cyclone progresses through the stages of birth, growth, and decay.
• Stages of cyclone life –
o Stationary front: a trough of lower pressure with higher pressure on both sides. Cold air to the north and warm air to the south flow We also discuss several other topics like Which of the three main processes of urine formation involves movement of waste from the peritubular capillary network to the distal convoluted tubule of a nephron so that it’s added to urine?
parallel to the front, but in opposite directions. This type of flow sets up a cyclonic wind shear
o Frontal wave: a cold front pushing southward and a warm front moving northward. The region of lowest pressure is at the junction of the two fronts. As the cold air displaces the war air upward along the cold front, and as war air rises ahead of the warm front, a narrow band of precipitation forms.
We also discuss several other topics like What is fdic (1934)?
o Open wave: The central pressure of the wave cyclone is now much lower, and several isobars encircle the wave’s apex. These more
tightly packed isobars create a stronger cyclonic flow, as the winds swirl counterclockwise an downward toward the low’s center.
Precipitation forms in a wide band ahead of the warm front and along a narrow band on the cold front.
o Mature (initial occlusion): the cold front eventually overtakes the warm front and the system becomes occluded. (This is when the
storm is the most intense!)
o Advanced occlusion: This happens as the occluded front becomes fully developed. Without an ample supply of energy of rising, warm, moist air, the system will dissipate.
o Cut-off cyclone: This is the end stage where a precipitation-free area is observed. In addition, only a weak cyclonic circulation is seen in the wind field. We also discuss several other topics like Who wrote “an essay on the principle of population” (1798)?
Don't forget about the age old question of Professional dental supply has been successfully selling dental instruments to dentists for the past 20 years, and has developed strong customer relations. when looking for new marketing opportunities, professional dental supply will most likely look firs
o What is a weather forecast – 1. Weather forecasting is the application of science and technology to predict the state of the atmosphere for a given location. 2. Weather forecasts are issued to save lives, to save property and crops, and to tell us what to expect in our atmospheric environment.
o Weather organizations – World Meteorological Organization (WMO) is a UN agency that makes sure that observation procedures do not vary among nations. Weather observations from all around the world are sent to The United States National Weather Service (NWS) branch: National Center for Environmental Prediction (NCEP) – this is where they analyze the data. If you want to learn more check out What is magneto-optic disk?
o Watch - indicates that atmospheric conditions favor hazardous weather occurring over a particular region during a specified time period, but that the actual location and time of the occurrence is uncertain.
o Warning – indicates that hazardous weather is either imminent or actually occurring within the specified forecast area.
o Advisory – issued to inform the public of less hazardous conditions caused by wind, dust, fog, snow, sleet, or freezing rain.
o How do we observe weather - http://www.rmets.org/weather-and climate/observing Don't forget about the age old question of The dots around the symbol of lewis electron-dot symbol, represents what?
o Meteograms – a chart that shows how one or more weather variables has changed at a station over a given period of time.
o Soundings – a two-dimensional vertical profile of temperature, dew point, and winds.
o Numerical weather prediction, MOS, ensemble forecasting o Numerical weather prediction uses mathematical models of the atmosphere and oceans to predict the weather based on current weather conditions.
o Model Output Statistics (MOS) is a technique used to objectively interpret numerical model output and produce site-specific guidance. o Ensemble forecasting is a numerical weather prediction method that is used to attempt to generate a representative sample of the possible future states of a dynamical system.
o Types of forecasting methods (i.e. persistence, analog, etc.) o Persistence forecast: a prediction that future weather will be the same as present weather.
o Steady-state or trend forecasting: because surface weather systems tend to move in the same direction and at approximately the same speed as they have been moving, one can forecast when and where the weather will arrive.
o Analogue method: It involves examining today's forecast scenario and remembering a day in the past when the weather scenario looked very similar (an analog). The forecaster would predict that the weather in this forecast will behave the same as it did in the past.
o For example, suppose today is very warm, but a cold front is approaching your area. You remember similar weather conditions one last week, also a warm day with cold front approaching. You also remember how heavy thunderstorms developed in the afternoon as the cold front pushed through the area. Therefore, using the analog method, you would predict that this cold front will also produce thunderstorms in the afternoon.
o Statistical method: forecasts made routinely of weather elements based on the past performance of computer models.
o Probability forecast: A probability forecast specifies how likely a defined event is to occur, as a percentage, and can help users to assess the risks associated with particular weather events to which they are sensitive.
o Types of forecasts (i.e. nowcast, short-range, etc.)
o Nowcast: a forecast for up to a few hours (usually not more than 6) o Short-range forecast: forecasts that range from about 6 hours to a few days (generally up to 3 days or 72 hours).
o Medium-range forecast: extends from about 3 to 8 days.
o Long-range forecast: extends beyond 8 days.
o What determines the movement of a weather system? o For short time intervals, mid-latitude cyclonic storms and fronts tend to move in the same direction and at approximately the same speed as they did during the previous six hours
o Low-pressure areas tend to move in a direction that parallels the isobars in the warm air ahead of the cold front
o Lows tend to move toward the region of greatest surface pressure drop, whereas highs tend to move toward the region of greatest surface pressure rise.
o Surface pressure systems tend to move in the same direction as the wind at 5500m – the 500 mb level. The speed at which surface systems move is about half the speed of the winds at this level.
o Ordinary (air-mass) Thunderstorms – they go through multiple stages: o 1. Cumulus stage (or growth stage) they tend to form in warm, humid air masses away from significant weather fronts. A parcel of warm, humid air rises, it cools and condenses into a single cumulus cloud or a cluster of clouds. The clouds will continue to grow as long as it is constantly fed by rising air from below. There is no precipitation,
thunder, or lightning yet.
o 2. Mature Stage - Storm is most intense, cloud tops can reach the Tropopause - with overshooting tops, seen in satellite imagery. Ice and water are both present in the cloud and perhaps lightning and thunder. The storm is characterized by warm updraft and cold,
downdraft, with precipitation reaching the surface. The downdraft can produce strong, gusty winds at surface.
o 3. Dissipating stage - Storm is dominated by the downdrafts.
Precipitation intensity at the ground weakens and you end up with a cold pool of air at the ground and warm air aloft. Hence, the storm has stabilized the environment.
o Severe thunderstorms - The National Weather Service defines a severe thunderstorm as having large hail, at least 3/4 inches (0.75 inches) in diameter, and/or damaging winds, at least 58 mph, or 50 knots.
o Supercell thunderstorms – In a region where there is strong vertical wind shear (speed and/or directional shear), the thunderstorm may form in such a way that the outflow of cold air from the downdraft never undercuts the updraft. In such a storm, the windshear may be so strong as to create horizontal spin, which, when tilted into the updraft, causes it to rotate. Here is a more simple definition: An intense long-lasting thunderstorm with a single violently rotating updraft.
o Squall lines – multicell thunderstorms may form as a line of thunderstorms. The line of storms may form directly along a cold front and extend for hundreds of kilometers. Sometimes squall lines develop in the warm air mass tens to hundreds of kilometers ahead of a cold front.
o Roll clouds - A Roll cloud is a relatively rare, low-level horizontal, tube shaped accessory cloud completely detached from the cumulonimbus base, unlike the more common shelf cloud. When present, it is located along the gust front and most frequently observed on the leading edge of a line of thunderstorms, a cold front or line squalls. The roll cloud will appear to be slowly "rolling" about its horizontal axis.
o Downbursts - a strong downdraft that causes an outflow of damaging winds at or near the surface. These downdrafts are referred to as macrobursts or microbursts, depending on their size. Downbursts are a serious hazard to aircraft, especially during takeoffs and landings, because they produce large and abrupt changes in the wind speed and direction near the ground.
o Flash floods – floods that develop with little to no advance warning. Floods can cause a massive amount of damage and kill people.
o Q: What causes rising motion? A: Convergence at the surface!
o Lightning – a discharge of electricity, a giant spark, which usually occurs in mature thunderstorms. (Check out this website for a clear explanation: http://www.britannica.com/science/lightning-meteorology)
o Lightning occurs when regions of excess positive and negative charge develop within the cloud. Typically, there is a large volume of positive charge in the upper regions of the cloud, a large negative charge in the center, and a small positive charge in the lower regions. These charges reside on water drops, ice particles, or both.
A preliminary breakdown process within the cloud initiates
cloud-to-ground lightning, typically between the center region of negative charge and the small positive charge below it. This process
creates a channel of partially ionized air—air in which neutral atoms and molecules have been converted to electrically charged ones. Next, a stepped leader (initial lightning stroke) forms and propagates downward, following channels created by the preliminary breakdown process. The leader is highly branched in the direction of its propagation. Most leader channels are negatively charged. When the stepped leader nears the ground, an upward, connecting discharge of opposite polarity rises and meets it at a point typically about 30 meters (100 feet) above the ground. When the junction is complete, the cloud is effectively connected to the ground, and a very bright return stroke propagates back to the cloud at a speed about one-third the speed of light, following the leader channel.
Lightning may travel within a cloud, from one cloud to another, from a cloud to the surrounding air, or from a cloud to the ground. The lightning stroke can heat the air through which it travels to an incredible 54,000 degrees F (which is 5 times hotter than the surface of the sun!). This extreme heat causes the air to expand explosively, thus initiating a shock wave that becomes a booming sound wave (thunder).
o What is a tornado – A tornado is a rapidly rotating column of air extending down from a cumuliform cloud that blows around a small area of intense low pressure with a circulation that reaches the ground. (https://www.youtube.com/watch?v=BMLZpjRYK9Q)
o What are the different parts of a tornado? (I.e. wall cloud, funnel cloud, etc.) A funnel cloud is used to refer to a visible funnel that does not tough the ground (If one just sees a funnel cloud, there might or might not be a tornado…it might look as if there is no tornado because it isn’t touching the ground, but don’t be so sure!).
o What is the life cycle of a tornado
▪ Dust-whirl stage: where dust swirling upward from the surface marks the tornado’s circulation on the ground and a short
funnel often extends downward from the thunderstorm’s base. ▪ Mature stage: damage is most severe during this time as the funnel reaches its greatest width and is almost vertical.
▪ Decay stage: the tornado begins stretching into the shape of a rope. The tornado becomes thinner and greatly distorted
before it finally dissipates.
o Q: What are the ideal conditions for the formation of a tornado? ▪ The answers are on this website!
o Watches vs. warnings:
o A Tornado watch is issued by the NOAA Storm Prediction Center meteorologists who watch the weather 24/7 across the entire U.S. for weather conditions that are favorable for tornadoes. A watch can cover parts of a state or several states. Watch and prepare for severe weather and stay tuned to NOAA Weather Radio to know when warnings are issued.
o A Tornado warning is issued by your local NOAA National Weather Service Forecast Office meteorologists who watch the weather 24/7 over a designated area. This means a tornado has been reported by spotters or indicated by radar and there is a serious threat to life and property to those in the path of the tornado. ACT now to find safe shelter!
o How are tornadoes classified?
o Q: How do tornadoes form?
▪ A: They are usually the extreme result of a supercell thunderstorm. During the storm cold air and warm air
combine in a set pattern: the cold air drops as the warm air rises. The warm air eventually twists into a spiral and forms the funnel cloud that we all associate with a tornado.
o How are tornadoes forecasted? What instrument is used? ▪ Doppler radars
o Distribution of tornado occurrences
o Hurricanes: an intense storm of tropical origin, with sustained winds of at least 64 knots (74mi/hr.), and with considerably higher gusts, which forms over the warm northern Atlantic and eastern north pacific oceans.
o Anatomy of a hurricane:
o Eye: the relatively clear area at the center. Within the eye, winds are light and clouds are mainly broken. The surface air pressure is VERY low, around 955mb.
o Eyewall: adjacent to the eye is the eyewall, a ring of intense thunderstorms that whirl around the storm’s center and may extend upward to almost 18 km above sea level. (Heaviest precipitation is in the eyewall)
o Q: Where do you have rising motion? Sinking motion? And what kind of weather would you expect with each?
o Q: What is needed for a hurricane to form? What will cause a hurricane to strengthen? Dissipate?
o A: Hurricanes form over tropical waters where the winds are light, the humidity is high in a deep layer extending up through the
troposphere, and the surface water temperature is warm, typically 26.5 degrees C (80 degrees F) or greater, over a vast area. These conditions usually prevail over the tropical and subtropical North Atlantic and North Pacific oceans during the summer and early fall.
o As long as a hurricane has a heat source, aka the water stays at 80 degrees F, it will survive.
o Hurricanes weaken rapidly when they travel over colder water and lose their heat source.
o Q: Why don’t hurricanes form over the equator?
o A: Hurricanes do not form over the equator because the Coriolis effect is 0.
o Q: How do hurricanes form?
o A: http://spaceplace.nasa.gov/hurricanes/en/
o A: http://earthobservatory.nasa.gov/Features/Hurricanes/
o What are the different stages for a hurricane?
o Tropical depression: the winds increase to between 20 and 34 knots and several closed isobars appear about its center on a surface weather map.
o Tropical storm: when the isobars are packed together and the winds are between 35 and 64 knots (at this point, the storm gets a name) o Hurricane (tropical cyclone): when wind speeds reach 64 knots.
o Q: What wind speeds are needed to classify a storm as a hurricane? o A: at least 64 knots or 74mi/hr.
o Q: How are hurricanes classified?
o A: The Saffir-Simpson Hurricane Wind Scale
o Q: How are hurricanes named?
o A: http://oceanservice.noaa.gov/facts/storm-names.html
On the next page you will find the alphabetized names for hurricane naming: no need to memorize!!! Just something to know about.