Chapter 2: Atmospheric Mechanics of Winds, Clouds and Moisture, and Atmospheric Stability

CHAPTER TWO

Atmospheric Mechanics of Winds, Clouds and Moisture, and Atmospheric Stability

200.

INTRODUCTION

This chapter introduces the student to the concepts associated with large- and small-scale wind

systems, the relationship between atmospheric temperature, moisture content, major cloud types,

and their effects on flight, as well as the various terms and requirements used to describe

atmospheric stability and instability.

Additionally, it covers a wide range of topics basic to the understanding of weather phenomena.

After an introduction to the meteorological station model, used in this chapter mainly to show

wind direction in diagrams, we build upon the pressure basics presented in Chapter One to

determine why winds blow in the particular direction that they do. To keep our analysis as

simple as possible, we will focus only on winds in the Northern Hemisphere. Since winds and

some forces in the Southern Hemisphere are a mirror image, discussing both patterns at this stage

would unnecessarily complicate things for a first-time introduction to weather.

The next topic covered is atmospheric moisture. Since most weather hazards have something to

do with moisture, it is important to understand how air becomes saturated, and how this will

affect the formation of clouds, fog, and precipitation. In fact, the two main types of precipitation

match up with two types of clouds. Clouds are classified according to the altitude of their bases,

and this chapter covers four major types of cloud. Eventually (and usually more often than

desired) all aviators will fly into clouds and thus an understanding of cloud composition and

activity will be essential to this course.

Cloud types can be a visual signal of atmospheric stability or instability. These two conditions

can be a further indication to meteorologists as well as to aircrew regarding the various weather

and flight conditions that may be encountered. There can be great differences in the expected

weather found between stable and unstable conditions, each with their own particular hazards to

flight. Consequently, knowing the relationships between atmospheric stability and flight

conditions could prove invaluable to an aviator.

201.

LESSON TOPIC LEARNING OBJECTIVES

Terminal Objective: Partially supported by this lesson topic:

2.0

Upon completion of this unit of instruction, student aviators and flight officers will

demonstrate knowledge of meteorological theory enabling them to make intelligent

decisions when confronted with various weather phenomena and hazards.

Enabling Objectives: Completely supported by this lesson topic:

2.12

Explain the term pressure gradient.

2.13

Explain Coriolis force and its apparent effect on wind.

Atmospheric Mechanics of Winds, Clouds and Moisture, and Atmospheric Stability

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