Balloon flights in the lower troposphere have to contend with various winds and
the decrease of temperature and pressure with altitude. In the upper troposphere
there have been major problems due to the extremely low temperatures and their
effects on the envelope of the balloon. The temperature averages −51°C (−60°F)
near the tropopause, the boundary with the stratosphere. The film of the envelope
can become very brittle. Balloons have failed and their missions lost. NASA and
their balloon manufacturers made major efforts to investigate this problem and to
develop and test alternate films to solve it; successfully. Then in the stratosphere
the temperature begins to increase, attaining an average of −15°C (5.0°F) near the
mesosphere.
The stratosphere is stratified (layered) in temperature, with warmer layers higher
and cooler layers nearer the Earth. This increase of temperature with altitude is a
result of the absorption of the Sun’s ultraviolet radiation by the ozone layer. This is
in contrast to the troposphere below, in which the temperature decreases with altitude. Temperatures also vary within the stratosphere as the seasons change,
Fig. 1.1 The atmosphere. A look at our atmosphere from the U.S. Space Shuttle with
cumulonimbus clouds, the troposphere (orange), stratosphere (white-blue), and mesosphere (dark blue) areas indicated. Photo courtesy of NASA.
Introduction 3
the decrease of temperature and pressure with altitude. In the upper troposphere
there have been major problems due to the extremely low temperatures and their
effects on the envelope of the balloon. The temperature averages −51°C (−60°F)
near the tropopause, the boundary with the stratosphere. The film of the envelope
can become very brittle. Balloons have failed and their missions lost. NASA and
their balloon manufacturers made major efforts to investigate this problem and to
develop and test alternate films to solve it; successfully. Then in the stratosphere
the temperature begins to increase, attaining an average of −15°C (5.0°F) near the
mesosphere.
The stratosphere is stratified (layered) in temperature, with warmer layers higher
and cooler layers nearer the Earth. This increase of temperature with altitude is a
result of the absorption of the Sun’s ultraviolet radiation by the ozone layer. This is
in contrast to the troposphere below, in which the temperature decreases with altitude. Temperatures also vary within the stratosphere as the seasons change,
Fig. 1.1 The atmosphere. A look at our atmosphere from the U.S. Space Shuttle with
cumulonimbus clouds, the troposphere (orange), stratosphere (white-blue), and mesosphere (dark blue) areas indicated. Photo courtesy of NASA.
Introduction 3