Pressure and Isobars

• Concept: Pressure changes perpendicularly to isobars.
• Isobars: Lines on a weather map representing points of equal atmospheric pressure.

Norwesters

• Occurrence: Typically occur during the afternoon.
• Definition: Norwesters are seasonal wind phenomena, often bringing sudden gusts or thunderstorms.

Altimeters and Altitude Measurement

• Measurement: Altimeters measure altitude based on mean sea level.
• Usage: Provides the aircraft’s height relative to the standardized mean sea level, crucial for maintaining consistent altitude references.

Stability of Air Masses

• Decreased Stability: Heating from below decreases stability, leading to rising air and potential cloud formation.
• Stable vs. Unstable Air: Stability affects weather patterns; unstable air often leads to cloud development and precipitation.

Ice Pellets and Freezing Rain

• Ice Pellets: Indicative of freezing rain, where rain droplets freeze before hitting the ground.
• Significance: A warning of possible ice on surfaces, which can affect aviation safety.

Wind Formation

• Cause: Winds are primarily caused by pressure differences between areas.
• Pressure Gradient: The larger the difference (or gradient), the stronger the wind.

Isobars and Surface Winds

• Closely Packed Isobars: Indicate strong winds at the surface.
• Weather Maps: Closer isobar spacing on maps shows areas with significant pressure gradients, leading to high wind speeds.

Tropopause Height

• Approximate Height: The tropopause lies around 11 km above the Earth’s surface.
• Function: Acts as a boundary between the troposphere and the stratosphere, impacting weather patterns.

SPECIs and METARs

• Definition: Types of meteorological observations providing current weather conditions at airports.
• Usage: Important for pilots to assess real-time weather changes and make informed decisions.

Cloud Formation