Question

If divergence in the jet stream above a surface low-pressure center exceeds convergence at the surface, will surface winds likely get stronger or weaker? Explain.

Short answer

Surface winds become stronger as the low-pressure area intensifies.

Step-by-step solution

Understanding Divergence and Convergence

Divergence in the jet stream is when air particles spread out or move away from each other, while convergence at the surface is when air particles move together or towards each other. It is crucial to understand that divergence leads to a lifting effect, drawing air upwards, which affects surface pressure systems.

Effect of Divergence Exceeding Convergence

If divergence in the jet stream above a surface low-pressure area exceeds the surface convergence, it means that more air is leaving the region aloft than entering it at the surface. This 'loss' of air aloft enhances the low-pressure system because less air mass means lower pressure at the surface.

Impact on Surface Winds

As the pressure in the low-pressure center decreases due to excess divergence aloft, the pressure gradient between the low-pressure center and the surrounding area increases. This increase in the pressure gradient results in stronger surface winds as air flows more rapidly from areas of high pressure to low pressure.

Key concepts

Jet Stream

The jet stream is a fast-flowing ribbon of air, high in the atmosphere, that travels across the Earth. It plays a significant role in weather patterns and meteorological phenomena. The jet stream is located at approximately 10 kilometers (around 6 miles) above sea level and can reach speeds of up to 300 kilometers per hour (about 186 miles per hour).

It forms due to the temperature differences between polar and tropical air masses. These differences create wind patterns that race around the globe in a westerly direction. The jet stream influences where and how weather systems, such as low-pressure systems, develop and move.

• Acts as a barrier between cold and warm air masses.
• Guides storm systems and influences weather patterns.
• Can affect flight paths due to its strong winds.

Underneath the jet stream, weather patterns can change rapidly, which makes understanding it vital for meteorology.

Surface Low-Pressure Systems

Surface low-pressure systems, commonly referred to as cyclones, are regions where the atmospheric pressure is lower than in the surrounding areas. These systems are associated with unsettled weather, like clouds, rain, and storms.

The formation of a low-pressure system occurs when warm, moist air rises, creating a region of lower pressure beneath. As the air rises, it cools and condenses, forming clouds and precipitating.

• Promote cloud formation and precipitation.
• Associated with convection and rising air currents.
• Often lead to stormy weather conditions.

Understanding these systems is essential for predicting changes in weather, as they can lead to significant weather events.

Divergence and Convergence

Divergence and convergence are key processes in meteorology that affect atmospheric motion and weather patterns.

Divergence occurs when air moves away from a common point. In the context of the jet stream, divergence aloft means that air is spreading out at high altitudes, leading to upward motion in the atmosphere beneath. This upward motion can cause clouds and rain if the air is moist.

• Encourages upward motion and can enhance low-pressure systems.
• Leads to cloud formation and potentially precipitation.

On the other hand, convergence involves air coming together at one point, often near the Earth's surface. This influx of air can result in compressed air masses and downward motion, potentially stabilizing weather conditions. However, if convergence happens at the surface beneath a diverging jet stream, it can enhance upward motion and low-pressure systems.

Pressure Gradient

The pressure gradient is the rate at which atmospheric pressure changes between two points at the same altitude. It is a driving force in creating wind patterns.

In meteorology, the greater the pressure gradient, the stronger the wind. This is because air moves from areas of high pressure to areas of low pressure along the gradient. The speed of the wind is proportional to the steepness of the pressure gradient.

• Stronger pressure gradients result in higher wind speeds.
• Key factor in determining wind direction and strength.
• Closely linked with surface weather conditions.

Understanding pressure gradients is crucial for predicting wind patterns and their impact on weather conditions.

Surface Winds

Surface winds are the flow of air along the Earth's surface, driven by the pressure gradient. They are influenced by various factors, including the Earth's rotation, topography, and atmospheric conditions.

As air moves from high-pressure to low-pressure areas, it creates wind. The strength and direction of these winds are determined by the Coriolis effect, friction with the Earth's surface, and the steepness of the pressure gradient.

• Drive weather systems and influence temperature distribution.
• Affected by friction, causing slower speeds close to Earth's surface.
• Can accelerate weather changes by moving air masses.

Surface winds are a fundamental component of our climate system and play a key role in weather patterns across the globe.