ATPL Meteorology - Class 12: Wind II.

Summary

This meteorology video explores the formation of various wind patterns, focusing on low-level and high-level winds. It explains how sea breezes occur due to land and sea's differing heat absorption rates, leading to pressure differences and air flow. The video also covers mountain-related winds like anabatic and catabatic winds, valley winds, and the fohn effect. High-level winds, influenced by temperature variations, are discussed, including the concept of thermal wind and jet streams, which can significantly impact flight times and experiences.

Takeaways

• 🌀 Sea breezes are formed due to the land and sea absorbing heat at different rates, leading to a pressure differential that causes air to flow from the sea to the land during the day.
• 🌃 At night, the process reverses, creating a land breeze where air flows from the land out to the sea as the land cools more quickly than the sea.
• 🏞️ Anabatic winds occur in mountainous areas where air rises up the slopes due to heating, creating a cycle similar to sea breezes but vertically along the slopes.
• 🌄 Valley winds are the result of horizontal winds being funneled through gaps between mountains, creating fast-flowing winds in the valley due to the venturi effect.
• 🔥 The Föhn wind, or Föhn effect, is a warm, dry wind that occurs on the leeward side of a mountain range, caused by air descending and warming up after rising and cooling on the windward side.
• 🏔 Mountain waves are oscillations in the wind that form on the leeward side of a mountain range, sometimes resulting in lenticular clouds and turbulent winds below.
• 🌡️ Thermal wind is a high-level wind caused by temperature differences between air masses, leading to a pressure gradient that is influenced by the Coriolis effect.
• ✈️ Jet streams are fast-flowing, narrow air currents in the upper atmosphere, formed by the combination of thermal winds and the temperature differences between air masses.
• 🌍 In the Northern Hemisphere, jet streams generally flow from west to east due to the Coriolis effect and the temperature gradient between the equator and the poles.
• 🌬️ The strength and direction of winds, including sea breezes, anabatic winds, and jet streams, can be influenced by the Coriolis force, which causes winds to turn right in the Northern Hemisphere and left in the Southern Hemisphere.

Q & A

What causes a sea breeze?

A sea breeze is caused by the differential heating of land and sea. The land heats up more quickly than the sea, causing the air above it to expand and create a low-pressure area. This results in cooler, denser air from the sea moving towards the land to equalize the pressure difference, creating a sea breeze.

How does the temperature difference between land and sea affect wind patterns?

The temperature difference between land and sea leads to different rates of heat absorption and radiation. This causes pressure differences that influence wind patterns, such as the formation of sea breezes during the day and land breezes at night.

What is an anabatic wind?

An anabatic wind is a type of local wind that occurs in mountainous areas. It is characterized by air being heated and rising up the slopes of mountains, creating a low-pressure area at the surface that draws in cooler air from the surrounding areas.

What factors contribute to the formation of a valley wind?

Valley winds are formed due to the topography of valleys. The wind is funneled through the valley, creating a venturi effect, which accelerates the wind speed. This can be influenced by the presence of mountains, which can also lead to anabatic or catabatic winds.

Why does the air cool as it rises in an anabatic wind?

The air cools as it rises in an anabatic wind due to adiabatic expansion. As the air ascends, it expands against the lower atmospheric pressure, doing work on the surroundings, which results in a decrease in temperature.

What is the difference between a sea breeze and a land breeze?

A sea breeze occurs during the day when the land heats up more than the sea, causing air to flow from the sea towards the land. Conversely, a land breeze occurs at night when the land cools more rapidly than the sea, leading to air flowing from the land out to the sea.

How do mountain waves form?

Mountain waves form when strong winds blow across a mountain range with a stable layer just above it. This causes a wave-like oscillation on the lee side of the mountain, which can extend for hundreds of nautical miles under the right conditions.

What is a thermal wind?

A thermal wind is a wind that is influenced by temperature differences between air masses. It is a result of the pressure gradient force caused by these temperature differences, which is then modified by the Coriolis effect, leading to winds that flow along the boundary between warm and cold air masses.

How do jet streams form?

Jet streams form due to significant temperature differences between air masses. They are fast-flowing, narrow air currents that occur at high altitudes, typically where there is a strong temperature gradient and a stable layer of air above the peak of a mountain range or due to the large-scale circulation patterns in the atmosphere.

What is the significance of lenticular clouds in relation to mountain waves?

Lenticular clouds are indicative of mountain waves. They form at the crest of the wave patterns and are a sign of strong, stable airflow over mountainous terrain. Their distinctive, lens-shaped appearance is caused by the rising and sinking air currents associated with mountain waves.