Recording-2025-03-07T14_59_00.244Z

Circulation Features

• Subtropical Highs: Well-developed areas of high pressure over the ocean.

• Wind Circulation:

  • Northern Hemisphere: High-pressure systems circulate clockwise.

  • Southern Hemisphere: High-pressure systems circulate counterclockwise.

• Temperature Convergence:

  • The point where polar and subtropical air masses meet leads to the greatest temperature contrast in the world.

Importance of Upper Atmosphere Winds

• Primary Westerly Winds:

  • The movement of wind is predominantly from the west in both hemispheres, which is crucial for understanding weather patterns.

  • Most weather flows eastward due to these winds.

• Key Concepts Influencing Wind:

  • Radiation and Temperature Gradient:

    • Low latitudes receive more solar radiation leading to warmer temperatures, while high latitudes have colder temperatures.

  • Air Pressure Variation:

    • Air pressure decreases with altitude due to the weight of the air above.

  • Density of Air:

    • Cold air is denser and heavier than warm air, affecting pressure and wind behavior.

Pressure Gradient and Wind Speed

• Pressure Measurement:

  • Dashed lines illustrate pressure drop (e.g., from 1000 to 900 millibars) with altitude.

• Impact of Temperature on Pressure:

  • In warm air, pressure decreases slowly with altitude due to lower density; in cold air, it decreases rapidly due to greater density.

Wind Speed Dynamics

• Wind Speed Increase with Altitude:

  • Wind speeds grow stronger as altitude increases, primarily because of reduced friction near the surface.

  • At high altitudes, friction becomes negligible, allowing winds to accelerate further.

• Pressure Gradient Impact:

  • Greater pressure gradients occur due to the differing air densities as one rises through warm versus cold air, resulting in stronger winds at higher levels.

Jet Streams

• Characteristics of Jet Streams:

  • Jet streams are relatively weak but exist as winds that are located around 25 to 30 degrees latitude in each hemisphere.

  • These jet streams can influence climate but are not directly associated with major weather systems.