Baroclinic vs. Barotropic Weather Environments Part 3

Good morning everyone visiting zoomradar, stormchasers, meteorology students, and professional meteorologists. My name is Brandon brady and I am installing my latest blog on Baroclinic vs Barotropic weather environments. This is my second to the last blog on this subject, essentially the third in the series. Today I am going to write about specific examples of weather systems that are associated with Baroclinic and Barotropic weather systems. The first part of the series covered what Baroclinic and Barotropic is, essentially defining each one. The second part went into the modeling of each weather system with one specific example in Baroclinicity. This installment covers all specific examples of both weather environments. Let’s begin.

I am going to touch on High Pressure Systems and Low Pressure Systems so I want to give you some brief insight on different levels upper and surface levels of each system.

1. UPPER LEVEL HIGHS – (Ridges) -Warm Core Highs or Weak Low Pressure. Thick layers in warm Regions, any maximum in Pressure (height) can be called a High pressure System.

2. UPPER LEVEL LOW – (Troughs) – Cold Core Lows or Weak High Pressure. Thinner Layers in cooler Regions, any minimum in Pressure (height) can be called a Low Pressure System.

3. Important Note – It is possible to have a Surface Low Pressure and a Upper level High Pressure just above it, in the upper troposphere. Also strong cold temps near the surface will likely lead to Low pressure or a trough in the upper parts of the troposphere. Conversely, if you could have an upper level High Pressure System a Warm Core High in the Upper levels and or a Warm Core Low pressure directly below it. This is a classic Tropical Low Pressure setup, such as, a tropical Storm or Hurricane.

I . BAROTROPIC WEATHER SYSTEMS – I know I stated in previous blogs that Barotropic weather conditions usually have no advections, fronts, etc. For the most part this is true, but that doesn’t mean they don’t have different weather systems with them. In this section you will be provided with specific weather systems in the genre.

1. Cold Core Barotropic Lows –

These Low Pressure have cold air throughout their systems, especially at the core. There is no strong differential in temperature within the Low Pressure System, essentially these are weak Low Pressures or in a state of weakening in a dissipation stage. The most Common type of Barotropic Low Pressure is Occlusion Lows. Occlusion Lows have the coldest Air at the center, north of the Polar Front Jetstream.

1b. Cut Off Lows –

The Low Pressure systems are isolated. These Upper level Lows usually occur south of the Polar Front Jetstream. They usually have a weak circulation associated with it and very difficult to identify at he surface. These Barotropic cut off lows are handled poorly by long range and short range computer forecast models.

source tornado.sfsu.edu

This is a classic example of a cold core barotropic low pressure system. This is a cut off low pressure in the upper levels that has dug west and southwest of Baja California. This system is cold throughout the entire system. I wouldn’t be surprised if rain/t-storms with small hail was occurring in the highlands of the Baja.

2. Warm Core Barotropic Lows –

These Barotropic Lows are located in the Tropics or occur in Deserts of the world. They have warm air throughout their entire system. The have very low surface pressure, in fact, cyclonic circulation weakens with height and may become high pressure aloft. In essence, Strong Low Pressure at the surface and High Pressure sitting above it or aloft. These Low Pressure Systems are located South of the Polar Front Jet, and are caused by low level heating of air Masses or differential heating of Land/Water Bodies.

Examples –

A. Thermal or Heat Lows – These Low Pressure Systems occur in the Deserts of the World usually the Hot Deserts of the World. For example, The Desert Southwest of the United States, The Sahara Desert in Northern Africa, The Kalahari and Namib in Southern Africa and the Great Victoria Desert in Australia are prime examples of Hot Deserts where Thermal Lows reside.

B. Tropical Cyclones – These Low Pressure Systems thrive on warm ocean temperatures above 80 degrees Fahrenheit. These Cyclones get fueled by adiabatic energy and differential heating. There are no fronts associated with these systems nor is there any advections of cold or warm air. These awesome systems get fueled by the release of Latent Heat of Condensation. These process is very dynamic as it involves three states of matter: Solid liquid and gas, actually liquid and gas. The energy released in the condensation process is phenomenal, for water to transform from a vapor or gaseous state to a liquid is an astounding 600 calories per gram of 80+ degree water. That’s incredible can you imagine an large amount of ocean basin at 80+ degree water temperature, Awesome. The power that these tropical systems have is unfathomable.

source www.gpb.org

Latent Heat release within the Hurricane continues to feed or “FUEL” the Storm, making a WARM CORE BAROTROPIC SYSTEM.

3. Cold Core Barotropic Highs –

These High Pressure Systems usually occur in the “wake” of a cold front. When I mention “wake” in meteorological terms this refers to after or behind a main feature. Cold Core Barotropic Highs have weak circulation with gaining height, and usually are associated with Polar Air Masses, behind cold fronts associated with Mid-Latitude Cyclones. These features develop in High Latitudes, cover large spatial areas, produce synoptic scale subsidence and have Cold Air throughout their System, once again there are no fronts and weak circulation associated with them. As you can see folks this is a defining characteristic of Barotropic weather systems.

source www.meted.ucar.edu

As you can see the cold air “bleeding” or slow flowing into the region of warm air depicted by the isotherms present. This depiction shows a cold barotropic high with very cold surface temperatures.

4. Warm Core Barotropic Highs –

The Warm Core Barotropic High circulation strengthens with height. A classic example of a Barotropic high is the Subtropical High Pressure System. These are the largest High Pressure Centers, as well as, the largest warm highs.

A. Subtropical High Pressure(STH) – These features are found at 30 degrees north and south latitude, these systems actually form the trade winds in the tropics and a main part in their formation. These high pressure systems are “Belts” of Highs between the easterly trade winds and the mid-latitude westerly winds. They really have a hand in forming both the easterly trade winds and the westerly mid-latitude winds. The Subtropical High Pressure Systems are very large, and in fact these systems stretch from the surface to the stratosphere. In the tropics or subtropics that is much deeper or farther than in the polar regions. In the tropics the stratosphere starts at about 60,000 feet, and in the polar regions it is have that height, so that is amazing. STH’s are also several thousand kilometers wide, so they are very sprawling features that can reside throughout most of a subtropical ocean basin or a land mass that is situated at or near 30 degrees latitude. A great example of a Subtropical High Pressure is the Bermuda-Azores High. This High Pressure system plays a role in a warm humid climate over the eastern U.S. and the Monsoon in the desert Southwest in the summer months.

Example :

Bermuda Highs – These High pressure Systems are also called Dynamic Anti-Cyclones due to their continues existence, it can’t be explained thermally, unlike Plateau Highs that form at higher elevations due to radiational cooling, or Cut-Off Highs that are located north of the Polar Front Jet and are rare and weak. Bermuda Highs- are due to Quasi Geostrophic Balance, this is due to a equal balance between Pressure gradient Force and Coriolis Force in the upper levels. This balanced pressure field is evident between easterlies in the tropics and westerlies in the mid-latitudes. The Bermuda-Azores high Pressure System is situated between the Tropical Hadley Cell in the South and the Mid-latitude Ferrel Cell to the North. On the eastern flank of the high pressure in the Mediterranean there is a dry climate that features dry winters and relatively wetter summers, as well as a sprawling Sahara Desert in Northern Africa. Conversely, the Western flank of this high pressure System is where the Eastern United States is located. The summers here are usually hot and humid, enough fuel to promote thunderstorms with heavy rain, frequent lightning and small hail. In fact, Florida is considered the lighting capital of the United States due in part to the positioning of the Bermuda High.

source www.meted.ucar.edu

The classic setup of the Bermuda Azores High sprawling over the Subtropical Atlantic. This feature is continuous and dominant.

5. Cutoff Lows and Highs –

This last part on barotropic features I do want to briefly write about “blocking” of weather features in the atmosphere.

A. Blocking – this occurs when the Polar Front Jetstream makes a loop far to the North or far to the South. What constituents a block? A block disrupts the normal zonal flow of the westerlies in the mid-latitudes. This results in a “block” or a blocking pattern that disrupts the normal westerlies. A pertinent example is the OMEGA BLOCK.

source www.firstwarnweatherteam.blogspot.com

This is an example of barotropic cutoff low and high pressure systems. The weather systems are shaped like the last letter in the Greek Alphabet Omega. As you can see The low pressure trough are dug in deep and look pretty strong and the High is dominant here as well. You can see flooding rains as a result of this pattern in the southern plains due to the fact there is very little to no movement in these features. In the Northeast cool and persistent light rain and just miserable weather there. All the while dry tinder conditions in the Upper great lakes and Southern Canada.

I am going to add the fourth series next week because I didn’t realize how much time I was going to spend on the Barotropic features. I try to put my everything into these blogs, to be informative and entertaining, and all the while not to be too long. So I am going to add the last series in a week or so on Baroclinic systems and the stages of a Mid-Latiude Cyclones since that is the Meat and Potatoes of baroclinic weather systems. I want to thank my dear friend and the Best MET Jeff B. and I thank you all for reading this blog I hope I educated and entertained today.

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