24-Weather+Theory-1-Slides

Overview

• Introduction to weather theory concepts covering atmosphere, Coriolis force, measurement of atmospheric pressure, wind, and currents.

Atmosphere Composition

• Major Gases:

  • 78% Nitrogen (N2)

  • 21% Oxygen (O2)

  • 1% Other Gases (including Argon and Carbon Dioxide)

  • Water Vapor: Varies from 0-5% by volume; significant for weather changes.

Layers of the Atmosphere

• Four Main Layers:

  • Troposphere:

    • Contains most weather phenomena (clouds, storms).

    • Extends from 4 to 12 miles at poles, up to 48,000 feet at the equator.

    • Average temperature decreases about 2°C for every 1,000 feet.

  • Stratosphere:

    • Contains the ozone layer, extending from 16 to 50 km above Earth.

    • Temperature increases with altitude due to ozone absorption.

  • Mesosphere:

    • Ranges from 50 to 80 km above Earth.

    • Temperature decreases as altitude increases, can drop to -90°C.

  • Thermosphere:

    • Located from 80 to 640 km above Earth, it absorbs solar radiation, leading to high temperatures (up to 230°C).

    • Contains the ionosphere which can affect radio communications.

Atmospheric Circulation

• Causes of Air Movement:

  • Uneven heating of Earth's surface creates changes in air movement and atmospheric pressure.

  • Warm air rises, cool air sinks, leading to circulation patterns.

Coriolis Force

• Definition: A force created by Earth's rotation.

• Effects:

  • Deflects air to the right in the Northern Hemisphere.

  • Changes with latitude and the speed of moving bodies.

  • Results in three distinct circulation cells in each hemisphere (Hadley, Ferrel, Polar).

Pressure Measurement

• Barometers:

  • Mercurial Barometer: Measures atmospheric pressure by height of mercury in a tube.

  • Aneroid Barometer: Uses an expanding/contracting sealed cell for pressure readings.

Standard Atmospheric Pressure

• Standard sea level pressure is defined as 29.92"Hg (1013.2 mb).

• Lines of equal pressure (isobars) are used to analyze pressure systems:

  • High Pressure: Surrounded by lower pressure.

  • Low Pressure: Surrounded by higher pressure.

  • Ridges and Troughs: Areas of elongated high and low pressure, respectively.

Wind Patterns**

• Highs and Lows: Air flows from high to low pressure, creating different weather conditions:

  • Highs: Anti-cyclonic, often associated with good weather.

  • Lows: Cyclonic, can produce clouds and precipitation.

• Definitions:

  • Convection: Vertical transport of atmospheric properties.

  • Advection: Horizontal transport of atmospheric properties.

Effect of Surface Conditions

• Convective Currents: Caused by uneven heating, leading to local winds like sea and land breezes.

• Surface obstructions can affect wind flow, creating potential hazards for aviation.