What is global circulation? | Part Two | The three cells
Summary
TLDRThis 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.
Outlines
🌍 Global Heat Distribution and Atmospheric Circulation
This paragraph discusses how the Earth's varying heat absorption due to its rotation and land-sea distribution leads to a complex global circulation system. Without rotation, a simple landmass would have a single cell circulation pattern, but the Earth's rotation and unequal land-ocean distribution create a 3-cell pattern in each hemisphere. The Hadley cells at the equator cause warm air to rise and spread out under the tropopause before descending and returning to the equator. Polar cells involve cold air descending in polar regions and rising as it warms up. Ferrel cells, unlike the others, are not temperature-driven and flow in the opposite direction, acting as a gear in the system. These cells result in semi-permanent high and low-pressure areas, influencing climatic zones and weather patterns.
Mindmap
Keywords
💡Equator
💡Poles
💡Hadley Cells
💡Polar Cells
💡Ferrel Cells
💡Global Circulation
💡Tropopause
💡High Pressure
💡Low Pressure
💡Jet Streams
Highlights
Different parts of the Earth heat up differently, with the equator receiving more heat from the Sun than the poles.
The purpose of global circulation is to redistribute this heat.
Without Earth's rotation and with no oceans, there would be a single circulatory cell in each hemisphere.
Hotter air would rise at the equator and flow toward the poles in a simple landmass scenario.
Air would sink as it cools and then return towards the equator.
The unequal distribution of land and ocean and the speed of Earth's rotation complicate the circulation system.
This results in a 3-cell pattern in both the northern and southern hemispheres.
The largest cells are the Hadley cells at the equator, where warm air rises to about 18 kilometers.
The tropopause acts as a lid to the lowest part of the atmosphere containing all weather.
Warm air spreads towards the poles, cooling and sinking before descending back to the surface.
The smallest cells are the polar cells, where cold dense air descends in polar regions.
Ferrel cells exist between the Hadley and polar cells and are not driven by temperature.
Ferrel cells flow in the opposite direction to the Hadley and polar cells, acting like a gear.
Circulating cells transport heat from the equator to the poles and create semi-permanent high and low-pressure areas.
Areas of low pressure where air is rising tend to have more rainfall, such as rainforests near the equator.
Areas of high pressure where air is descending have clear skies and little rainfall, leading to desert regions.
Not all deserts are hot; Antarctica is a cold desert under the descending branch of the Polar cell.
Antarctica is the largest and driest desert, despite more precipitation falling in the Sahara.
The rotation of the Earth gives us jet streams and prevailing winds, which will be explained in the next video.
Transcripts
the last video showed that different
parts of the earth heat up differently
with the equator receiving more rates of
heat from the Sun than the poles and the
purpose of global circulation is to
redistribute this heat if the earth did
not rotate and was a simple landmass
with no oceans we would have a single
circulatory cell in each hemisphere
where hotter air would rise at the
equator and flow toward the poles the
air would sink as it cools and then
returned towards the equator but the
unequal distribution of land and ocean
and the speed of the Earth's rotation
make this circulation system more
complicated giving us a 3-cell pattern
which exists in both the northern and
southern hemispheres the largest cells
are the Hadley cells at the equator the
warmer less dense air rises it rises to
a height of about 18 kilometers and
spreads out underneath the tropopause
the tropopause acts as a lid to the
lowest part of our atmosphere which
contains all of our weather the warm air
spreads out towards the poles gradually
cooling and sinking as it moves before
descending to the surface and flowing
back to the equator the smallest cells
are the polar cells cold dense air
descending in the polar regions flows at
low levels to about 60 to 70 degrees
north or south as the air leaves the
polar regions it starts to warm and rise
returning to the poles at high levels
between the Hadley and polar cells are
the feral cells unlike the other cells
the feral cells are not driven by
temperature
these cells flow in the opposite
direction to the Hadley and polar cells
acting like a gear these circulating
cells not only transport heat from the
equator to the poles but also results in
semi-permanent areas of high and low
pressure due to the rising and
descending parts of the circulation
cells giving us our climatic zones where
air is rising an area of low pressure is
created so these areas seem much more
rainfall this is why the largest areas
of rainforests are found near the
equator and why the United Kingdom has a
relatively wet climate where air is
descending an area of high pressure
forms giving largely clear skies and
little rainfall which leads to the
desert regions but not all deserts are
hot Antarctica
sits under the descending branch of the
Polar cell and is also classed as a
desert with more precipitation falling
in the Sahara Antarctica is the largest
and driest deserts overall check out our
video on atmospheric pressure for more
on how pressure leads to weather our
next video shows how the rotation of the
earth gives us jet streams and
prevailing winds
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