Meteorology and Aviation

Introduction to Meteorology

• Meteorology is the scientific study of the atmosphere and weather, crucial for aviation.
• Weather and human factors are major causes of aviation accidents.
• Technological advancements have reduced material failure, but weather remains uncontrollable.

Importance of Meteorology

• Weather conditions like visibility, rain, snow, thunderstorms, icing, crosswinds, clouding, turbulence, and wind shear affect flight safety.
• Extreme weather can halt flights or prompt diversions.
• Understanding meteorology aids in making timely and safe flying decisions.

The Atmosphere

• Definition: Gaseous volume surrounding any planet.
• Extent: Starts from Earth's surface up to 800 km into space.
• Layers:
  • Homosphere: Up to 80 km, uniform composition.
  • Heterosphere: Above 80 km, varied composition.

Composition of the Atmosphere

• Gases:
  • Nitrogen: 78%
  • Oxygen: 21%
  • Argon: 0.95%
  • Carbon Dioxide: 0.03%
• Nitrogen and oxygen ratio: 4:1 by volume, 3:1 by weight.

Atmospheric Properties

• Heat: Poor conductor of heat and electricity.
• Heating source: Mainly from Earth’s re-radiation, not direct solar radiation.

Greenhouse Gases

• Types: Water vapor, carbon dioxide, methane.
• Effects:
  • Maintain Earth's average temperature at 15°C.
  • Prevent drastic temperature drops.
  • Excess gases contribute to global warming.

Air and Humidity

• Water Vapor: Lighter than air, rises.
• Humidity Levels:
  • Saturated air: 100% relative humidity.
  • Dry air: Relative humidity less than 100%.
• Temperature Impact: Warmer air holds more water vapor.

Ozone Layer

• Protects from UV rays.
• Located between 10 to 50 km, peak concentration at 20-25 km.

Atmospheric Layers

• Troposphere:
  • Height: 0 to 11 km.
  • Temperature decreases with height (lapse rate: 6.5°C/km).
  • Contains 3/4 of atmospheric weight, most weather phenomena.
• Tropopause:
  • Boundary where temperature stop decreasing.
  • Height varies with latitude.
• Stratosphere:
  • Height: 11 to 50 km.
  • Temperature stable initially, then increases with height.
  • Low humidity and stable conditions.
• Mesosphere:
  • Height: 50 to 80 km.
  • Temperature decreases with height.
• Thermosphere:
  • Begins at 80 km, temperature increases with height.

International Standard Atmosphere (ISA)

• Standardized atmospheric conditions for aircraft and engine testing:
  • Dry air.
  • MSL temperature: 15°C.
  • MSL pressure: 1013.25 hPa.
  • MSL density: 1.225 kg/m³.
  • Lapse rate: 6.5°C/km up to 11 km.
  • Tropopause temperature: -56.5°C.

Impact of Atmosphere on Flying

• Lapse Rate: Freezing levels occur above 3-4 km.
• Oxygen Requirements: Additional oxygen needed above 3 km.
• Weather Phenomena: Mostly occur below 11 km.
• Aircraft Performance: Deteriorates with altitude due to reduced air.
• Instrumentation: Affected by changes in pressure, temperature, and density.

End of lecture notes on the atmosphere as part of meteorology for aviation.