AP Environmental Science 4.5 - Global Wind Patterns
Summary
TLDRIn this educational video, Mr. Smith explores Global Wind Patterns, explaining how the Earth's rotation, the Sun's energy, and air properties like density and moisture content influence atmospheric circulation. He delves into the Hadley cell, illustrating how warm air rises at the equator, cools, and precipitates, while also discussing the Coriolis effect's impact on wind direction. The video aims to help viewers understand the environmental factors behind these global weather patterns, using visual models to clarify complex concepts.
Takeaways
- 🌍 The Earth's rotation and the basic properties of air, such as density, are fundamental to understanding global wind patterns.
- 🌞 The intensity of the Sun's energy at the equator causes warm air to rise, leading to the formation of the Hadley cell, which is a key component of global wind patterns.
- 🔥 Warm air is less dense than cold air and holds less moisture, which is why it rises and leads to precipitation as it cools and expands.
- 🌧️ Precipitation forms when the water vapor in rising warm air condenses due to cooling, which is a significant part of the atmospheric circulation process.
- 🔄 The Hadley cell is a circulation pattern between 0 and 30 degrees latitude, responsible for global wind patterns and the distribution of deserts and rainforests.
- 🏜️ Deserts typically form around 30 degrees north and south latitude due to the sinking of dry air, creating high-pressure systems.
- 📉 Air pressure differences cause air to move from high-pressure areas near 30 degrees towards low-pressure areas at the equator and 60 degrees.
- 🌀 The Coriolis effect, caused by Earth's rotation, deflects the path of winds and other moving objects, influencing wind direction and ocean currents.
- 🌬️ The trade winds between 0 and 30 degrees blow from east to west due to the Coriolis effect, impacting weather patterns and ocean circulation.
- 🌪️ Between 30 and 60 degrees, the westerlies blow from west to east, influenced by the Earth's faster rotation at lower latitudes.
- 📚 Understanding the relationships between the Sun's energy, air properties, and the Coriolis effect is essential for explaining global atmospheric circulation and weather patterns.
Q & A
What are the three basic factors that influence atmospheric circulation?
-The three basic factors that influence atmospheric circulation are the intensity of energy from the Sun, properties of air such as density, and the spinning of the Earth on its axis, which produces the Coriolis effect.
Why does warm air rise and how does it affect weather patterns?
-Warm air rises because it is less dense than cold air. As warm air rises, it cools and expands, leading to the condensation of water vapor into liquid, which forms precipitation such as rain or snow. This process affects weather patterns by causing precipitation in certain areas.
What is the Hadley cell and how does it influence global wind patterns?
-The Hadley cell is a cycle of air circulation between 0 and 30 degrees latitude. Warm air rises at the equator, cools and spreads out, then sinks back down at 30 degrees north and south. This cycle influences global wind patterns by creating predictable wind and weather patterns, such as trade winds and desert formations at 30 degrees.
How does the Sun's energy impact air circulation at the equator?
-Sunlight is most direct at the equator, causing air to warm and rise. As the warm air rises, it cools and expands, leading to condensation of water vapor into rain. This results in intense rainfall at the equator.
Why do deserts typically form around 30 degrees north and south latitude?
-Deserts form around 30 degrees north and south latitude because the air that descends back to Earth at these latitudes is very dry. The cool, dry air creates high-pressure areas, leading to arid conditions and desert formation.
What causes air to move from high-pressure to low-pressure areas on Earth’s surface?
-Air moves from high-pressure to low-pressure areas due to the pressure gradient force. At 30 degrees, the high-pressure system causes air to flow towards the low-pressure system at the equator and towards 60 degrees latitude, creating wind patterns.
How does the Earth's rotation affect wind patterns?
-The Earth's rotation causes the Coriolis effect, which deflects the path of moving air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This deflection results in curved wind patterns instead of straight north-south movement.
What is the Coriolis effect and how can it be understood using a baseball example?
-The Coriolis effect is the deflection of moving objects, like wind, due to Earth's rotation. If you throw a baseball straight south from the North Pole, it will be deflected to the right because the ground beneath it is rotating. Similarly, wind is deflected as it moves across Earth's surface.
Why does wind between 30 and 60 degrees latitude move from west to east?
-Wind between 30 and 60 degrees latitude moves from west to east because the Earth at 30 degrees is spinning faster than at 60 degrees. This difference in rotational speed causes the wind to be deflected in the same direction as Earth's spin, resulting in westerlies.
How do global wind patterns influence ocean currents?
-Global wind patterns drive the circulation of ocean currents. In the Northern Hemisphere, winds create clockwise ocean currents, while in the Southern Hemisphere, they create counterclockwise currents. This movement of water affects climate and weather patterns globally.
Outlines
🌍 Introduction to Global Wind Patterns
Mr. Smith introduces the topic of global wind patterns, explaining that the session will cover the basic properties of air and the Earth's rotation, which are crucial for understanding atmospheric circulation and weather patterns. The objectives include explaining environmental factors that result in atmospheric circulation, focusing on the intensity of solar energy, air properties like density, and the Coriolis effect caused by Earth's rotation.
🌡️ Understanding Air Density and Moisture
The first factor influencing atmospheric circulation is air density. Warm air is less dense than cold air, causing it to rise. This concept is illustrated by the temperature difference between an attic and a basement in summer. Additionally, warm air holds less moisture than cold air, leading to dry winter skin. As warm air rises and cools, it expands, and the water vapor condenses into precipitation, which falls back to Earth. This rising and cooling process is part of the Hadley cell, explaining global wind patterns between 0 and 30 degrees latitude.
☀️ The Sun's Role in Atmospheric Circulation
The second factor is the energy from the Sun. Direct sunlight at the equator warms the air, causing it to rise, cool, and expand, leading to intense rainfall. This cycle contributes to predictable weather patterns, such as deserts at 30 degrees latitude where cool, dry air descends. The high pressure at 30 degrees and low pressure at the equator cause air to move along the Earth's surface back towards the equator, completing the Hadley cell cycle.
🌪️ The Coriolis Effect and Wind Direction
The third factor is Earth's rotation, which causes the Coriolis effect. Objects moving through the atmosphere are deflected due to the Earth's spin. For instance, a baseball thrown southward from the North Pole is deflected to the left. Similarly, wind between 0 and 30 degrees is deflected from east to west. Wind from 30 to 60 degrees moves in the same direction as Earth's spin, due to the varying speeds of Earth's rotation at different latitudes. This concept is illustrated using the analogy of switching between treadmills moving at different speeds.
🌀 Combining Factors for Global Wind Patterns
Combining solar energy, air properties, and the Coriolis effect reveals Earth's global wind patterns. The Hadley cell demonstrates air rising at the equator, sinking at 30 degrees, and moving back towards the equator and 60 degrees. The deflection caused by Earth's rotation results in Eastern trade winds and westerlies, influencing ocean currents and weather patterns. In North America, weather moves from west to east due to westerlies, affecting how weather forecasts are interpreted. The session concludes with a practice question on the Sun's role in air circulation patterns.
Mindmap
Keywords
💡Global Wind Patterns
💡Atmospheric Circulation
💡Coriolis Effect
💡Hadley Cell
💡Solar Energy
💡Air Density
💡Moisture Content
💡Precipitation
💡Deserts
💡Pressure Systems
💡Trade Winds
Highlights
Introduction to topic 4.5 on global wind patterns and their relation to atmospheric circulation.
Explanation of environmental factors affecting atmospheric circulation, including solar energy, air properties, and the Coriolis effect.
The concept that warm air is less dense than cold air, leading to its rise and the formation of weather patterns.
Warm air holds less moisture than cold air, which influences humidity and precipitation.
The process of warm air rising, cooling, expanding, and eventually condensing to form precipitation.
Description of the Hadley cell, a major air circulation pattern between 0 and 30 degrees latitude.
The role of solar energy in warming equatorial air and initiating the Hadley cell cycle.
How the condensation of water vapor in rising air leads to intense rainfall at the equator.
The formation of deserts around 30 degrees latitude due to descending dry air.
The movement of air from high to low pressure systems and its significance in the Hadley cell.
The impact of Earth's rotation on wind direction, introducing the Coriolis effect.
Illustration of the Coriolis effect using the analogy of throwing a baseball at the North Pole.
Explanation of how the Coriolis effect deflects wind direction in the Northern and Southern Hemispheres.
The concept of wind moving from east to west between 30 and 0 degrees due to the Coriolis effect.
The role of Earth's rotation speed in deflecting wind direction from west to east between 30 and 60 degrees.
The practical application of understanding wind patterns in predicting weather and ocean currents.
The integration of solar energy, air properties, and the Coriolis effect in shaping Earth's global wind patterns.
The significance of the Eastern trade winds in historical maritime trade and ocean current circulation.
The westerlies' influence on weather patterns in North America, with weather systems moving from west to east.
Encouragement to practice explaining relationships between environmental concepts using visual models.
Transcripts
everybody its mr. Smith and today we'll
be talking about topic 4.5 which is
global wind patterns so we'll be
learning how the basic properties of air
as well as how the rotation of earth
give us the wind patterns that we see on
earth and how they're also responsible
for the weather patterns that we see our
objective for the day is to be able to
explain environmental factors that
result in atmospheric circulation and in
order to do that we need to understand
three basic factors those are the
intensity of energy from the Sun
properties of air such as density and
the spinning of the earth on its axis
which produces something known as the
Coriolis effect our suggested science
skill to practice today is explaining
relationships between characteristics of
environmental concepts or models that
are presented visually so as I mentioned
the first factor that determines
atmospheric circulation is how airs
density changes under different
conditions so the first property of air
related to its density is that warm air
is less dense than cold air so it rises
if you've ever been in a house with an
attic in the summer the difference in
temperature between the attic and the
basement is a really great example of
this property we also need to understand
that warm air holds less moisture than
cold air so think about how dry and
cracked your skin gets in the winter
versus summer
that's because cold winter air holds
less moisture now another factor we need
to understand is that as warm air rises
it cools and that causes it to expand
and because cold air can't hold as much
moisture the water vapor that's in warm
rising air will condense into liquid
which forms precipitation in the
atmosphere and that eventually falls
down to earth as rain or snow or sleet
and finally after air has risen cooled
and expanded it's spread out and then
eventually it sinks back down and we'll
see that happen here in the diagram at
30 degrees north and south so these
properties of air help us understand the
diagram to the left here which is called
a Hadley cell the Hadley cell is this
cycle of air circulation between 0
degrees and 30 degrees and it's largely
responsible for our global wind patterns
on earth so now that we have our basic
properties of air down which is the
first factor influencing atmospheric
circulation now we're going to introduce
second factor which is energy from the
Sun so because sunlight is most direct
at the equator that's going to cause air
here to warm and rise so we can see that
as step one in the diagram as warm air
rises it cools and expands and because
cool air holds less moisture than warm
air the water vapor has to condense into
rain and so if we look at step two in
the diagram that's why we see such
intense rain at the equator because that
warm rising air has its water vapor
condensed and then fall down to earth is
rain in step three the air continues to
rise cool and expand further in step
four this air is expanding and spreading
out even further and then in Step five
we have cool dry air is sinking back
down to earth right around 30 degrees
north and south and as we can see in the
diagram this is going to explain why we
see this predictable pattern of deserts
forming all over the earth around 30
degrees north and south it's because the
air that's descending back down to earth
here is incredibly dry so we get deserts
however we're not quite done
understanding the Hadley cell if we look
at the diagram we'll see that we have
this arrow here that's going from 30
degrees back towards the equator so why
is air moving along Earth's surface from
30 degrees back to the equator well we
have high pressure at 30 degrees north
and south that's because we have this
column of cool dry air that's sinking
back down to earth and when a column of
air is pushing down on earth it gives us
high pressure meanwhile at the equator
we have low pressure and that's because
warm air being heated from the Sun is
rising at the equator and we know that
air moves from high to low pressure
so along Earth's surface we'll see this
air from 30 degrees flowing back towards
the equator that's because we're moving
from high to low pressure another way to
think about this though is we have to
get back to step one of the cycle
somehow and so we need replacement air
to come in and fill this vacuum or this
gap of air left by the air that's rising
at the beginning of the Hadley cell so
we've covered why air rises and expands
at the equator sinks back down at 30
degrees and then moves along Earth's
surface back towards
the equator but that's only two of the
three factors that determine atmospheric
circulation the third factor is Earth's
rotation so believe it or not if earth
were standing still rather than spinning
wind would move more or less just
straight north and south because the
earth is rotating though that means that
objects such as wind or this baseball
we'll talk about here in a second that
our traveling through Earth's atmosphere
are actually deflected in the opposite
direction of Earth's rotation so another
way to try to understand the Coriolis
effect is to imagine that you're
standing at the North Pole and you're
throwing a baseball straight south so
you may be aiming the baseball along
this line here
but because Earth's rotation is causing
the ground beneath the baseball to spin
the baseball will actually be deflected
the opposite direction of the spin so
even though the ball was traveling on
this trajectory it's going to end up
here to the left of where you aimed it
because the ground beneath the earth is
spinning now the same thing is true of
the wind between 0 and 30 degrees so
because this air at 30 degrees is moving
from a high pressure system back down to
a low pressure system it would flow
directly south are directly north in the
southern hemisphere but because earth is
spinning this direction the wind from 0
from 30 to 0 degrees is deflected the
opposite direction so what we get is
wind moving from east to west between 30
and 0 degrees now because 30 degrees is
a higher pressure area than 60 degrees
wind is also moving from 30 degrees out
to 60 degrees the wind in this direction
though is deflected in the opposite
direction as between 30 and 0 and that's
because the earth at 30 degrees is
spinning so much faster than it is at
higher latitudes at 80 or even at 60
that the wind is actually going to be
deflected in the same direction as
Earth's spin now that's a confusing
concept so let's talk about this using
the example of a treadmill imagine that
you're running along a treadmill that's
going 15 miles an hour and suddenly
you've jumped to a treadmill right next
to you moving in the same direction but
only
moving two miles an hour so it's moving
far more slowly you're going to have so
much momentum coming from the 15 mile an
hour treadmill that jumping onto the 2
mile an hour treadmill is going to cause
you to run forward quite a bit and so
that's why we see wind from 30 degrees
to 60 degrees actually traveling in the
same direction as Earth's spin it's
because the earth is spinning so much
faster at 30 degrees than 60 degrees
that the wind is deflected in that
direction of our spin now we'll put
together all three factors so the sun's
energy air properties like density and
the Coriolis effect to take a look at
how Earth's global wind patterns are the
result of those factors so the first
thing I want to do here is point out
that our Hadley cell here still works
the same way we're just looking at it
from a side view where we see all of
Earth rather than looking at it from the
viewpoint of being on Earth's surface
like we did in our first slide so if we
look at the Hadley cell we can remember
that the sun's rays are striking the
equator most directly so that's heating
the air here and causing it to rise then
it sinks back down at 30 degrees and
because of this high pressure system at
30 degrees air is going to be moving out
towards 0 degrees and 60 degrees we can
see here that with our low pressure at
the equator our higher pressure at 30
degrees and then our low pressure again
at 60 we're going to get air moving out
from 30 degrees towards 60 and towards
the equator but remember that the air
does not move in a straight line it's
deflected based on the direction of
Earth's spin and so between 0 and 30
degrees we have our air moving from east
to west and we call those Eastern trade
winds because they used to drive trade
from the east to the west because the
ships are dependent on sails this also
drives the circulation of the ocean
currents in a clockwise direction in the
northern hemisphere and in a
counterclockwise direction in the
southern hemisphere then remember that
between 30 and 60 degrees the wind is
blowing from west over to the east and
this is because the earth at 30 degrees
is moving so much faster than out at 60
degrees or 80 degrees that the wind is
deflected in that same direction as the
spin so it moves from west to east now
this means that in North America where
we live we get our weather from the West
so if you're looking at the radar to try
to see if we're going to have a snow day
you're gonna look over at Chicago and
Wisconsin because you know that their
storms are headed our direction because
we have westerlies or western prevailing
winds which means our weather moves from
the western United States over to the
eastern United States our suggested
science Gale for practice up for cue 4.5
today is explaining relationships
between characteristics of environmental
concepts or models that are represented
visually so I want you to see if you can
explain how is the Sun responsible for
the pattern of air circulation that we
see in cycles see on the diagram here
alright everybody thanks for tuning in
today don't forget to like this video if
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scholar
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