Sep 2012

Lesson 4.1

Meteorology

The Atmosphere

Reference

From the Ground UpChapter 6.1:The AtmospherePages 123 - 124

Introduction• Meteorology is the study of the Earth’s

atmosphere and the weather which occurs in it.

• It’s important for pilots to know about the weather since aircraft are much more dependent on it than ground-based vehicles.

Outline• Properties• Divisions• Standard Atmosphere

Properties• Composition:

– 78% nitrogen– 21% oxygen– 1% other = Argon, carbon dioxide, water vapour, etc

• Water vapour is most important component in terms of weather

• Properties of atmosphere (cause most weather):– Mobility– Compression– Expansion (most important)

EQUATOR

N

STroposphere

Stratosphere

Mesosphere

Thermosphere

Divisions• Troposphere

– Temperature and pressure decrease– Where most weather occurs– Almost twice as wide at equator than poles– Top layer is Tropopause

• Stratosphere– Temperature increases to 0°C due to Ozone Layer– Almost no water vapour or air currents– Top layer is Stratopause

Divisions• Mesosphere

– Temperature decreases to -100°C– Top Layer is Mesopause

• Thermosphere– Temperature increases indefinitely– Includes Ionosphere, which reflects certain radio

signals

• Exosphere– Pressure drops to vacuum– Auroras form– Merges into Space

Standard Atmosphere• ICAO standard atmosphere

– Air is perfectly dry gas– MSL pressure

= 29.92” Hg= 1013.2 hPa= 1013.2 mb= 101.3 kPa

– MSL temperature = 15°C– Lapse rate = 1.98°C per 1000 ft

Next Lesson

4.2 – MeteorologyClouds

From the Ground UpChapter 6.2:CloudsPages 124 - 127