Earth’s Atmosphere
In this section, you will learn about weather. Weather causes 25% of manned air operations, and 40% of aviation related fatalities. Weather systems can change as an aircraft travels through the sky, and as it changes altitude.
Earth's Atmosphere is 12 km thick: 78% nitrogen, 21% oxygen, 1% other elements.
The troposphere is the layer of the atmosphere where weather occurs, and where RPAS flies.
Atmospheric Layers
Atmospheric Pressure: measured by mercury in North America.
The Friction Layer: The lowest layer of the earth's atmosphere, usually up to 3,300 feet. Surface friction is effective in slowing down wind up to approximately 1,500 to 3,000 feet above the ground.
Air and Water Changes
Water vapour is an important part of the atmosphere that contributes to weather.
It can change in various ways:
Evaporation: the process of turning from liquid into vapor
Conducting: transferring of heat energy
Radiating: emitting of heat energy into the air
Recondensing: to cause (a vapour or other substance) to condense again
Image Source: https://okfirst.mesonet.org/train/meteorology/HeatTransfer.html
Other Concepts Associated with Water and Air
Relative humidity: temperature and pressure of air (amount of water vapor present in the air)
Dewpoint: 100% humidity (when air can no longer hold its air)
Air stability: affected by wind, thermal gradient, dew point
Altitude Increase: means temperature decreases, air pressure decreases