Figure 1-1 Thickness of the Earth's Atmosphere

CHAPTER ONE

AVIATION WEATHER

2.9

Define indicated altitude, calibrated altitude, Mean Sea Level (MSL) altitude, Above

Ground Level (AGL) altitude, pressure altitude, and density altitude.

2.10

Describe the effects of pressure changes on aircraft altimeters.

2.11 State the effects of temperature deviations from the standard lapse rate on aircraft

altimeters.

102.

REFERENCES

Weather for Aircrews, AFH 11-203, Volume 1, Chapters 1, 3, and 4.

Aviation Weather for Pilots and Flight Operations Personnel, Chapters 1-3.

103.

STUDY ASSIGNMENT

Review Chapter One and answer the study questions.

104.

THE ATMOSPHERE

The atmosphere is the gaseous covering of the Earth. This envelope of air rotates with the Earth

but also has a continuous motion relative to the Earth's surface, called circulation. It is created

primarily by the large temperature difference between the tropics and polar regions, and is

complicated by uneven heating of land and water areas by the Sun.

105.

ATMOSPHERIC LAYERS

If the Earth were compared to a baseball, the gaseous covering would be about as thick as the

baseball's cover (Figure 1-1).

Figure 1-1 Thickness of the Earth's Atmosphere

It is divided into layers that have certain properties and characteristics (Figure 1-2). The lowest

two layers are the troposphere and stratosphere, with the tropopause being a region between these

two. The troposphere is the layer adjacent to the Earth's surface. It varies in height from an

average 55,000 feet over the equator to 28,000 feet over the poles.

1-2

General Structure of the Atmosphere, and Atmospheric Temperature and Pressure