Homework 3 - Fronts and Cyclones

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School

Central Michigan University *

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Course

140

Subject

Geography

Date

Jan 9, 2024

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docx

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Uploaded by CommodoreViper3697

In this assignment we will learn about fronts and how they are related to midlatitude cyclones. Part I Types of Fronts A front is defined as the boundary between two airmasses. The major types being: mT - maritime Tropical (moist and warm) mP - maritime Polar (moist and cold) cT - continental Tropical (dry and warm) cP - continental Polar (dry and cold) When any of these airmasses meet, they form a front. Depending on which airmasses meet and which airmass is moving forward (and which is moving out of the way) you will have different kinds of fronts. The two main types of fronts are cold fronts, where cold air is advancing forward toward warm air, and warm fronts, where warm air is advancing forward toward cold air. This video gives a brief overview of these two types of fronts: Front overview Question 1: Describe three (3) differences between cold and warm fronts. Cold fronts move faster than warm fronts; Cold fronts lift warm fronts as the cold dense air is heavier; warm fronts bring moderate or longer lasting weather There are other types of fronts, however. When a cold or warm front stalls, or stops moving, we call this a stationary front. Also, in some cases, a cold front can catch up to a warm front and overtake it. When this happens, we call it an occluded front. This page reviews these four types of fronts, along with the types of weather they cause: University of Oklahoma - Fronts Question 2: Which type of front tends to produce the most violent weather among all frontal types? Cold Fronts Question 3: Why do you think that type of front has the most violent weather? Cold fronts move fast and maintain their intensity longer One final type of front is called a dry line. A dry line is a boundary between warm dry (cT) and warm moist (mT) airmasses. Dry lines are a common location for the formation of thunderstorms in the spring in the central United States. Part II Midlatitude Cyclones A midlatitude cyclone is a strong low pressure area located somewhere between 20-70 degrees north or south latitude. These cyclones usually have one or more fronts associated with them. This page describes an idealized model of a midlatitude cyclone in the northern hemisphere: University of Illinois Cyclone model Question 4: Why does there tend to be warm air ahead of the midlatitude cyclone? The warm front pushes northward and the cold front pulls southward; this leads to the mair being wrapped around low pressure.

As we learned previously, winds rotate counterclockwise around a low pressure system in the northern hemisphere. Therefore, we can use wind barbs on a weather map to help identify the location of the low. This page describes this process: University of Illinois - Winds around a Cyclone This rotation of the winds, transports airmasses from the south and from the north and wraps them around the midlatitude cyclone. This acts to intensify the cyclone and strengthen the fronts, or the boundaries between these airmasses. This page describes this process: University of Illinois - Movement of Airmasses Question 5: a. What is the general wind direction in the warm sector of a midlatitude cyclone? Northward b. What is the general wind direction in the cold sector of a midlatitude cyclone? Southward We can also use satellite imagery to identify the location of and weather associated with midlatitude cyclones. This satellite image shows a very well developed cyclone over the Great Lakes region: NASA Earth Observatory - Cyclone over the Midwest In this image, we see a typical "comma-shaped" cloud. This page shows some other examples of these cloud patterns: University of Illinois - Cyclones on Sattelite Imagery Here is a video showing a satellite loop of the development of one of these comma clouds: Development of a comma cloud Notice that the cloud pattern changes over the life of the storm and is never constant. Part III Searching for Cyclones Using what we have learned, we will now try to find some midlatitude cyclones over North America. Go to this page, showing the current location of fronts over the contiguous U.S. Today's surface analysis Right-click (or ctrl-click) and select "Save image." Upload the map when you submit the assignment. You can you this page to help you interpret the map if needed: NWS Front Symbols Question 6: Describe the location of any low pressure centers on the map, within the contiguous U.S. 1 in the Northwest (Or, ID, MT); Midwest (KS, MO, IL); Question 7: For EACH of the low pressure centers described in question 6, describe the location and type of any fronts that seem to be associated with each low. (i.e. is touching the low or extending out from the low). Northwest: Goes in between 2 lows; Midwest: going up to the low Now we will look at the current satellite imagery. Go to this page for satellite imagery: Real-time Weather Data Select "Infrared - Longwave" from the radio buttons on the left. Click on "Contiguous U.S." on the map. Right-click (or ctrl-click) and select "Save image." Upload the map when you submit the assignment. This map shows cloud top temperatures. Blues are higher colder cloud tops, while greens and yellows are lower warmer cloud tops. Oranges and reds are areas of no or very low clouds. Now we will compare the weather map to the satellite image. Look the two images side by side.

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