AWH 4-5

Chapter 4, The Earth’s Atmosphere 4-5 The regions of the stratosphere and the mesosphere, along with the stratopause and mesopause, are called the middle atmosphere. The transition boundary that separates the stratosphere from the mesosphere is called the stratopause. Please note that in this figure the temperature is not necessarily to scale with the height but provides an approximation of how the temperature changes with height. Figure 4-1. Vertical Structure of the Atmosphere 4.4 The Standard Atmosphere Continuous fluctuations of atmospheric properties create problems for engineers and meteorologists who need a fixed standard for reference. To solve this problem, they defined a standard atmosphere that represents an average of conditions throughout the atmosphere for all latitudes, seasons, and altitudes. Standard atmosphere is a hypothetical vertical distribution of atmospheric temperature, pressure, and density that, by international agreement, is taken to be representative of the atmosphere for purposes of pressure altimeter calibrations, aircraft performance calculations, aircraft and missile design, ballistic tables, etc. (see Table 4-2 and Figure 4-2). Weather-related processes are generally referenced to the standard atmosphere, as are the examples in this handbook.