Describe the stages of development of an ordinary cell thunderstorm

Aviation Weather

Overview & Objectives:

In Chapter 9, we will study the movement of the air in more detail. The chapter begins by describing the various scales of atmospheric motion, and the weather phenomena that fall into each of those scales. The focus of the rest of the chapter is on the smaller end of the atmospheric motion scale, starting with very small (micro) scale wind phenomena called eddies, then going into the somewhat larger scale (mesoscale) local wind phenomena like land and sea breezes, mountain and valley breezes, katabatic winds, and chinooks. Local wind phenomena greatly influence local weather patterns, and can even cause adjacent geographic areas to experience vastly different weather conditions. An understanding of local wind patterns is a very important aspect of flight safety.

In Chapter 10, we will study the global wind system, the largest scale of atmospheric motion. Global winds transport air around the entire planet, and allow weather events that happen in one part of the world to influence the weather thousands of miles away. Global winds also steer the movement of mid-latitude cyclones and hurricanes. The jet stream is part of the global wind system – a fast-moving current of air found in the upper troposphere, which is an important “propagator” of commercial aircraft. In this chapter, we will also explore the important interactions taking place between the air and the ocean, and the processes by which each influences the other.

Upon successful completion of this module, you will be able to:

Differentiate between atmospheric phenomena at various scales of atmospheric motion. (LO 5)

Describe the causes and effects of thermal and mechanical turbulence in the atmosphere. (LO 2, 3)

Explain the development of various local wind systems. (LO 5)

Interpret wind direction according to convention in meteorology. (LO 2)

Apply the single-cell and three-cell conceptual models in explaining the observed circulation of the atmosphere at the global scale. (LO 5)

Differentiate between the polar front jet and sub-tropical jet streams. (LO 5, 7)

Discuss the impacts of air-sea interaction on weather and climate. (LO 2, 5)

Apply local and global winds and their measurement to everyday life or aviation. (LO 8)

Extra Resources:

https://youtu.be/Ye45DGkqUkE

https://www.weather.gov/jetstream/itcz

https://www.weather.gov/jetstream/seabreeze

Week 7

Overview & Objectives:

In this module, we will describe air masses, large bodies of air that form over a vast region of ocean or land. Air masses are defined by their overall temperature and humidity characteristics, which determines their overall density. When air masses of different density interact, the less dense, and typically also more humid, air mass will be forced to rise over the denser air mass, producing weather. The boundary along which different air masses do battle is called a weather front.

Air masses are brought together, and weather fronts are created, within mid-latitude cyclones – low-pressure systems that extend through every level of the troposphere. In this module, we’ll also study the structure and developmental stages of mid-latitude cyclones and weather fronts, and apply this understanding in analyzing them on weather maps.

When mid-latitude cyclones and their associated weather fronts move over a location, they typically produce significant changes in the local weather conditions over a short period of time. The weather produced within mid-latitude cyclones and along weather fronts also present several hazards to aviation.

Upon successful completion of this module, you will be able to:

Differentiate between the types of air masses influencing weather in North America. (LO 2, 3, 5)

Explain the causes and effects of air mass modification. (LO 2, 3, 4, 5)

Connect air mass interaction with weather fronts. (LO 2, 3, 4, 5, 6)

Differentiate between the structure and characteristics of the various types of weather fronts. (LO 2, 3, 4, 5, 6)

Describe the typical progression of weather during frontal passage for the various types of weather fronts. (LO 2, 3, 4, 5, 6)

Identify, on a surface weather map, the air masses and weather fronts associated with a mid-latitude cyclone. (LO 6, 7)

Describe the idealized structure and evolution of a mid-latitude cyclone. (LO 6)

Apply the basic concepts of air masses, weather fronts, and mid-latitude cyclones to everyday life or aviation. (LO 8)

Synthesize numerous weather concepts and their applications to flight in outlining potential weather impacts to aviation operations at regional airports. (LO8)

Extra Resources:

https://www.youtube.com/watch?v=o4lg8UfY5DM

https://www.weather.gov/jetstream/synoptic_intro

http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/home.rxml

Week 8

Overview & Objectives:

In this module, we will build our pyramid of weather knowledge even higher, in exploring the various forms of convective weather generated by atmospheric instability. Discussing the physical and thermodynamic principles required for convective weather development will bring together all of the concepts we have covered in the course to this point.

The ordinary, or single cell, thunderstorm is the simplest example of convective weather - these short-lived weather features are typical on a warm, humid, conditionally unstable summer afternoon, and illustrate the local atmosphere "stabilizing itself".

Things get really interesting when individual thunderstorms become locally numerous, or organize along a cold front, squall line, or within tropical low pressure systems (i.e., a hurricanes - the topic of Module 9). Things get even more interesting when atmospheric conditions within the warm sector of a mid-latitude cyclone come together to generate supercell thunderstorms, these large, rotating thunderstorms, which have the potential to generate large, damaging tornadoes.

To meet the objectives for this module, focus on gaining a general understanding of the following important aspects of convective weather phenomena:

The stages of development of ordinary cell (air mass) thunderstorms.

The structure and characteristics or the various types of thunderstorms (ordinary, supercell, multi-cell, squall line, derecho).

The weather condition that exists in the development of severe thunderstorms, that enhances their strength and longevity over that of ordinary thunderstorms.

The specific criteria that classify a convective storm as severe.

The difference in meaning and wording of weather watches versus weather warnings issued by the National Weather Service.

We will, of course, also apply the dangerous aspects of convective weather phenomena to their associated hazards in both everyday life and aviation.

Upon successful completion of this module, you will be able to:

Describe the characteristics, development, structure, and resulting weather hazards, for the following convective weather features: ordinary thunderstorm, multicell thunderstorm, supercell thunderstorm, microburst, squall line, dry line thunderstorms, derecho, mesoscale convective complex. (LO 6)

Differentiate between ordinary and severe thunderstorms in terms of their development and characteristics. (LO 6)

Describe the development, structure, and categorization of tornadoes. (LO 3, 6)

Explain the development of lightning. (LO 6)

Determine whether a thunderstorm would be officially categorized as severe. (LO 6)

Identify, using weather charts and satellite imagery, the components of a severe thunderstorm. (LO 6, 7)

Corellate concepts related to various convective weather phenomena to their impacts in everyday life or aviation. (LO 8)

Extra Resources:

https://www.weather.gov/lwx/warningsdefined

https://www.weather.gov/jetstream/tstorms_intro

https://www.weather.gov/jetstream/lightning_intro

https://www.weather.gov/jetstream/derecho_intro

https://www.meted.ucar.edu/training_module.php?id=995#.X7-n8y_gG-q

http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/home.rxml

https://youtu.be/QCnRtX7UIe8

Week 9

Overview & Objectives:

Early in the course, we described how atmospheric and ocean circulations redistribute excess heat from the tropics toward the polar regions. Mid-latitude cyclones, studied in Module 7, and tropical cyclones (hurricanes), the topic of our final module, are storms that play a key role in that redistribution of energy.

Hurricanes are born over tropical waters as clusters of thunderstorms. We will explore the factors that create the ideal environment for thunderstorm clusters to organize into violent warm-core lows that transform enormous amounts of latent heat energy into wind energy. We will also discuss the aspects of a hurricane that have the potential to inflict catastrophic damage upon landfall.

As in previous modules, the study of hurricanes will tie in most of the concepts we’ve covered thus far in the course. We will explore the structure and development of hurricanes and apply that understanding in making a direct comparison between mid-latitude cyclones (the topic of Module 7) and tropical cyclones. We will also discuss the importance of collecting hurricane data for the generation and dissemination of weather products that provide information for mitigating the impacts, and increasing our understanding, of hurricanes.

Upon successful completion of this module, you will be able to:

Describe the anatomy, structure, stages of development, typical paths, naming conventions, and devastating aspects of a hurricane. (LO 2, 3, 4, 6)

List the necessary environmental conditions for hurricane formation and development. (LO 2, 3, 4, 6)

Discuss the mechanisms that weaken hurricanes. (LO 2, 3, 4, 6)

Compare hurricanes to mid-latitude cyclones in terms of structure, development, and weather conditions. (LO 3, 4)

Outline the hazards of hurricanes in everyday life or aviation. (LO 8)

Extra Resouces：

https://www.weather.gov/jetstream/tc

https://www.weather.gov/safety/hurricane

https://www.aoml.noaa.gov/hrd-faq/

https://youtu.be/zP4rgvu4xDE

https://youtu.be/SaqfCPCoIUE