What is global circulation? | Part Two | The three cells

Summary

This video script explains how Earth's uneven heating leads to global circulation patterns. With no rotation, a simple landmass would have one cell per hemisphere. However, Earth's rotation, land-sea distribution, and topography create a 3-cell pattern: Hadley (equatorial), Ferrel (mid-latitude), and Polar cells. These cells redistribute heat, creating climatic zones with varying weather patterns, such as rainforests near the equator and deserts in high-pressure areas. The script also hints at upcoming content on jet streams and prevailing winds.

Takeaways

• 🌍 The Earth's different regions heat up unevenly, with the equator receiving more heat than the poles.
• 🔄 Global circulation aims to redistribute this heat unevenly across the Earth.
• 🌬️ Without Earth's rotation and with no oceans, there would be a single circulatory cell in each hemisphere.
• 🌡️ The Hadley cells are the largest cells at the equator, where warm air rises and spreads out under the tropopause.
• 🌀 The Ferrel cells are mid-latitude cells that flow in the opposite direction to the Hadley and polar cells.
• ❄️ The polar cells are the smallest, with cold air descending in polar regions and flowing towards the mid-latitudes.
• 🌤️ The tropopause acts as a lid to the lowest part of the atmosphere, containing all of our weather.
• 🌧️ Rising air creates low-pressure areas, which are often associated with rainforests and wet climates.
• 🏜️ Descending air leads to high-pressure areas, resulting in clear skies and little rainfall, often found in desert regions.
• ❄️ Antarctica, despite being cold, is considered a desert due to its location under the descending branch of the Polar cell.
• 🌀 The Earth's rotation contributes to the formation of jet streams and prevailing winds.

Q & A

How does the Earth's rotation affect global circulation?

The Earth's rotation complicates the circulation system, leading to a 3-cell pattern in both the northern and southern hemispheres instead of a single cell.

What is the role of global circulation in redistributing heat?

Global circulation redistributes heat from the equator, which receives more heat from the Sun, to the poles.

What would happen if the Earth did not rotate and was a simple landmass with no oceans?

There would be a single circulatory cell in each hemisphere, with hot air rising at the equator and flowing toward the poles, then sinking and returning towards the equator.

What are the three types of cells in the Earth's circulation system?

The three types of cells are the Hadley cells, the polar cells, and the Ferrel cells.

How high do the warm air in the Hadley cells rise?

The warm air in the Hadley cells rises to a height of about 18 kilometers.

What is the tropopause and how does it relate to the Hadley cells?

The tropopause acts as a lid to the lowest part of the atmosphere, which contains all of our weather. The warm air from the Hadley cells spreads out underneath the tropopause.

What is unique about the Ferrel cells compared to the other cells?

The Ferrel cells are not driven by temperature and flow in the opposite direction to the Hadley and polar cells.

How do the rising and descending parts of the circulation cells create climatic zones?

Rising air creates areas of low pressure, leading to more rainfall, while descending air creates areas of high pressure, resulting in clear skies and little rainfall.

Why are the largest areas of rainforests found near the equator?

The largest areas of rainforests are found near the equator because of the low pressure created by rising air in the Hadley cells.

Why does the United Kingdom have a relatively wet climate?

The United Kingdom has a relatively wet climate due to the low pressure areas created by the rising air in the circulation cells.

Why are some deserts not hot, like Antarctica?

Antarctica is a desert under the descending branch of the Polar cell, and it is cold because it is at a high latitude where temperatures are generally lower.

What is the significance of the jet streams and prevailing winds in relation to the Earth's rotation?

The rotation of the Earth gives us jet streams and prevailing winds, which are not directly mentioned in the script but are related to the Earth's circulation patterns and can affect weather systems.