Section 2 EO M436.02 – DESCRIBE AIR MASSES AND FRONTS
Resources needed for the delivery of this lesson are listed in the lesson specification located in A-CR-CCP-804/PG-001, Proficiency Level Four Qualification Standard and Plan, Chapter 4. Specific uses for said resources are identified throughout the instructional guide within the TP for which they are required.
Review the lesson content and become familiar with the material prior to delivering the lesson.
Review and prepare the demonstration located at Attachment A.
Prepare the slides located at Attachments B and C.
Photocopy the handout located at Attachment D for each cadet.
Prepare the learning stations located at Attachments E–I.
Photocopy a set of the fronts worksheets located at Attachment J for each cadet.
Nil.
An interactive lecture was chosen for TPs 1 and 2 to orient the cadets to air masses and fronts and generate interest in the subject.
An in-class activity was chosen for TP 3 as it is an interactive way to present types of fronts and associated weather.
Nil.
By the end of this lesson the cadet shall be expected to describe air masses and fronts.
It is important for cadets to describe air masses and fronts as knowledge of this material helps them to understand changes in weather conditions. Being able to describe air masses and fronts provides knowledge for potential instructional duties and is part of the fundamentals that cadets pursing future aviation training will require.
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Teaching point 1
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Explain weather in an air mass.
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Time: 10 min
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Method: Interactive Lecture
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There are three main factors that determine the weather in an air mass:
moisture content,
the cooling process, and
the stability of the air.
Moisture Content
Continental air masses are very dry and little cloud develops. The high moisture content in maritime air may cause cloud, precipitation, and fog.
The Cooling Process
Even if the air is moist, condensation and cloud formation only occur if the temperature is lowered to the dewpoint. The cooling processes that contribute to condensation and the formation of clouds are:
contact with a surface cooling by radiation,
advection over a colder surface, and
expansion brought about by lifting.
Cloud formation within an air mass is not uniform. For example, clouds may form in an area where the air is undergoing orographic lift even though the rest of the air mass is clear.
The Stability of the Air
In stable air, stratus cloud and poor visibility are common, whereas in unstable air, cumulus cloud and good visibility are common.
Characteristics of Cold Air Masses and Warm Air Masses
Cold air masses (eg, arctic and polar air masses) will typically have the following characteristics:
instability,
turbulence,
good visibility,
cumuliform clouds, and
precipitation in the form of showers, hail, and thunderstorms.
Warm air masses (eg, tropical air masses) will typically have the following characteristics:
stability,
smooth air,
poor visibility,
stratiform clouds and fog, and
precipitation in the form of drizzle.
What are the three main factors that determine weather in an air mass?
What are the cooling processes that contribute to condensation and the formation of clouds?
What are the characteristics of a warm air mass?
Moisture content, the cooling process, and the stability of the air.
Contact with a surface cooling by radiation, advection over a colder surface, and expansion brought about by lifting.
Stability, smooth air, poor visibility, stratiform clouds and fog, and precipitation in the form of drizzle.
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Teaching point 2
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Define and explain types of fronts.
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Time: 15 min
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Method: Interactive Lecture
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A front is the transition zone between two air masses. The interaction of air masses along their frontal zones is responsible for weather changes.
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Conduct the demonstration outlined at Attachment A to illustrate the mixing of warm and cold air masses: (1)
Allow the cadets to move closer so they can observe what will happen. (2)
Have the cadets predict what will happen when the divider is removed. (3)
Observe the action between the red and blue colored water. |
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The blue-dyed water represents a cold air mass and the red-dyed water represents a warm air mass. The area where these two air masses meet and mix is a front. |
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Show the slides located at Attachment B as fronts are presented. |
The blue water (colder and more dense) will slide underneath the warmer water which is the same that occurs to the air.
The cold air mass is more dense and therefore sinks, undercutting the warm air which will ascend over the cold air.
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Show the slides located at Attachment C as front symbols are presented. |
An air mass is a large section of the troposphere with uniform properties of temperature and moisture in the horizontal. An air mass can be several thousands of kilometers across and takes on the properties from the surface over which it formed.
Formation over ice and snow of the artic will be dry and cold. Formation over the South Pacific will be warm and moist. Formation over a large body of water is moist and is referred to as maritime air. An air mass over a large land area is dry and is referred to as continental air.
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Distribute the handout located at Attachment D to each cadet. Cadets will label each symbol as the information is presented. |
Define a front.
What does the interaction of air masses along their frontal zones cause?
Explain what happens when a cold air mass and a warm air mass meet.
A front is the transition zone between two air masses.
Changes in the weather.
The air in a cold air mass is more dense and therefore sinks, undercutting the warm air. The air in a warm air mass will ascend over the cold air.
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Teaching point 3
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Conduct an in-class activity to describe types of fronts and associated
weather.
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Time: 55 min
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Method: In-Class Activity
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The objective of this activity is to have the cadets identify different types of fronts and their associated weather.
Pen / pencil,
Coloured pencils / markers,
Fronts information sheets located at Attachments E–I, and
Fronts worksheets located at Attachment J.
Set up and clearly mark five learning stations, located at Attachments E–I.
1.Distribute all five fronts worksheets and a pen / pencil to each cadet.
2.Divide the cadets into groups of two or three and place each group at one of the learning stations.
3.Have the cadets fill out the appropriate fronts worksheet for that station.
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At learning stations with more than one diagram the cadet can choose which one to draw. |
4.After nine minutes have the groups rotate to the next station until each group has completed all five stations.
5.Review the fronts worksheets as a class and answer any questions.
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The cadets' participation in the activity will serve as the confirmation of this TP.
What are the characteristics of a cold air mass?
What clouds indicate the passing of a warm front?
What is the term for the wedge-shaped mass of warm air lying above the colder air masses in an occluded front?
Instability, turbulence, good visibility, cumuliform clouds, and precipitation in the form of showers, hail, and thunderstorms.
Cirrus, cirrostratus, altostratus, nimbostratus, and stratus.
Trowal.
Nil.
This EO is assessed IAW A-CR-CCP-804/PG-001, Proficiency Level Four Qualification Standard and Plan, Chapter 3, Annex B, Aviation Subjects–Combined Assessment PC.
There are two basic types of weather: air mass and frontal. Knowledge of air masses and fronts is crucial for understanding weather patterns and making accurate predictions of changing weather conditions. This knowledge is essential for future aviation training and for potential instructional duties at the squadron.
It is recommended that the three periods required for this EO be scheduled consecutively.
Cadets who are qualified Advanced Aviation may assist with this instruction.
A3-044 CFACM 2-700 Air Command. (2001). Air Command weather manual. Ottawa, ON: Department of National Defence.
C3-116 ISBN 0-9680390-5-7 MacDonald, A. F., & Peppler, I. L. (2000). From the ground up: Millennium edition. Ottawa, ON: Aviation Publishers Co. Limited.
C3-334 Short, N. (2005). "Remote Sensing Tutorial". Federation of American Scientists. Retrieved February 26, 2009, from http://www.fas.org/irp/imint/docs/rst/Sect14/Sect14_1c.html
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