Investigation 8: Upper Air Winds
- Page ID
- 45358
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If you have ever flown on a cross-country flight before (Figure 8.1), you may have noticed that it's faster to travel from west to east than it is to fly from east to west. The reason is that flights fly through the upper troposphere, at about 30,000 feet, where strong winds generally blow from west to east. However, these winds are only one component of the upper troposphere's behavior, and what happens in the upper troposphere greatly influences the weather at the surface. We've already examined this effect when investigating stability and cloud formation. Wind direction and the general flow of the upper troposphere have significant implications for the kind of weather we get at the surface.
In this investigation, we will examine upper-air weather maps and identify the presence of troughs and ridges. We will also investigate any implications those features have on surface weather.
- Investigate upper-air maps at the 500 mb and 300 mb levels.
- Distinguish surface weather conditions from upper-air conditions.
- Identify key features in the jet stream, such as troughs, ridges, and jet streaks.
- 8.1: Pressure Levels and Heights
- The importance of monitoring atmospheric pressure levels, specifically the 500 mb and 300 mb heights, for understanding wind patterns and the jet stream is covered here. It outlines differences between upper-level and surface maps, such as the lack of cloud data and temperature units. Additionally, it highlights how altitude in station models correlates with temperature, indicating that warmer regions tend to have higher heights at the 500 mb level compared to cooler areas.
- 8.2: Troughs and Ridges
- Upper-level jet stream wave patterns, distinguishing between ridges (which transport warm air north) and troughs (which move cool air south) is explored. A February 28, 2025, 500 millibar map illustrates these patterns and their connection to the pressure gradient force. It also notes that upper-level winds are typically faster than surface winds, influenced by height line spacing, while consistent forces, except for friction, affect wind speed regardless of elevation.
- 8.3: Westerlies and the Jet Stream
- An analysis of 300 millibar winds and their importance in understanding the Jet Stream, contrasting it with the 500 millibar level. It explains how to interpret 300 mb maps, covering heights and the differences between zonal (straight west-to-east) and meridional (wavy with ridges and troughs) flows. The implications of these wind patterns for temperature and advection are discussed, noting that north/northwest winds can cause warm air advection in certain U.S. regions.
- 8.4: Convergence, Divergence, and Jet Streaks
- The significance of jet streaks in shaping surface weather through the alteration of upper tropospheric wind patterns is emphasized. It explains how convergence leads to faster winds and divergence causes slower winds, impacting mid-latitude systems and cyclogenesis. Identifying jet streaks aids meteorologists in forecasting weather changes, and a 300 mb weather map is included to illustrate these concepts.
- 8.5: Alternative Text Descriptions for Investigation 8
- A set of detailed alternative text descriptions for Investigation 6
Thumbnail: A diagram of the Jet Stream. Jet Stream Diagram by Fred the Oyster is licensed under CC-BY-SA 4.0.