Video 1.3.1 General atmospheric circulation

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Strategies for winning. Meteorology in a round the world regatta

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Universitat de Barcelona

Strategies for winning. Meteorology in a round the world regatta

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In this course you can learn about the mechanics of global weather, the foundations of ocean meteorology, predictive modeling and how sailors receive data via satellite and use high-performance navigation software. This course looks at oceanic meteorology and climatology through the lens of the sport of sailing. You will gain a basic knowledge of meteorology needed by sailors to take part in a regatta such as the Barcelona World Race, the only double-handed, round the world regatta with no stops. You will learn about the strategies employed during a round the world regatta and how these are put to use on board the latest ocean racing yachts.

À partir de la leçon

Understanding maritime meteorology

In this module you will learn the foundations for an understanding of general and in particular maritime meteorology. What are the factors and engines powering the weather? What do we need to know to understand the weather phenomena we experience every day? What do ocean sailors need to know to predict the weather? Instructors: Tomàs Molina, Santi Serrat

Video 1.3.1 General atmospheric circulation6:48

Video 1.3.1.4. Sailor experiences4:36

Video 1.3.2 The mechanics of global weather8:35

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Tomàs Molina

[MUSIC]

Let's talk now about the engines of global weather,

how the world will have different areas and what mainly

generates the types of weather that exist around of the world.

For that we are going to talk a little about the general atmospheric circulation,

and for that we are going to have to draw the world globe.

Surely you have heard of the general atmospheric circulation, that is

a thing that comes almost everywhere, so we will do it very quickly.

But, to understand better, we will draw it.

This is zero degrees of latitude, this is the Equator... Thirty degrees,

of latitude... Sixty degrees and ninety degrees, which are the poles.

You already know that the air on the Equator has a tendency

to rise because it is warmer, of course,

while on the poles, the air will descend.

How does the wind behave at all latitudes, in general?

It has been proven that the air has a tendency to rise here.

Climb here and descend here.

It rises in the 60's, descends on the poles.

It rises at 60, descends at 30.

And here you will notice

that it rises,

and with this a similar thing would happen.

These are different cells that are in different parts of the world.

Look at the rising area at Equator.

So what do we have at the Equator?

Basically storms that

are in the line with Equator.

What do we have at 30 degrees latitude?

As we have descent,

the air when it descends is heated, becomes more stable,

therefore around the 30 degrees of latitude we will have anticyclones.

And the same in the southern hemisphere.

In the 60 degrees we have rises,

therefore, we have lows again, depressions.

And what do we have at the poles?

So we have descent, anticyclones, and the same on the south hemisphere.

This is what shapes the position of the anticyclones and the storms.

But notice that at the same time, if here the air rises, and here it goes down,

the air would want to come from this area, where it goes down.

Where it descends to this area where it rises.

Therefore, between 30 and 60 there would have to be a wind current that

goes from north to south.

When the wind, in the northern hemisphere,

by effect of the force of Coriolis, it goes towards its right.

Therefore, note that this wind here, what it does is turn in this direction.

Notice that the winds that we have between the 30

and the zero degrees are of northeast component.

What happens between 30 and 60?

Notice that the wind would come down and want to turn up.

But as it moves to your right, notice that the wind does like so,

therefore the winds that we have between the 30

and the 60 are winds of the west.

For the same reason, here are from the east.

Here they are from the southeast,

Here they are also from the west and here they are again from the east.

Notice that in each place of the world, in each of these zones,

we'll see that weather moves in a different direction.

All of us who live in middle latitudes know that things,

weather, it moves from the west,

to the east, because we are in this zone of westerly winds,

but when we go to the Canaries or when we cross the Atlantic the winds are the

from the northeast, whose component is from the east to the northeast.

It would be the same in the southern hemisphere, between zero and 30.

Between the 30 and the 60 are the winds from the west.

Even here, as there is very little land, here it is called the Roaring Forties,

The Roaring Forties, the Furious Fifties and the Screaming Sixties,

because as there is no earth that can accommodate them, that can calm them down,

These winds from the west are very strong and sometimes they roar, or squeal, or moo.

And, further below of the 60 degrees south latitude,

they again have easterly winds.

Notice that this follows the logic of anticyclones and storms.

An anticyclone rotates in the clockwise direction, you notice that in the north

we are seeing winds of the west, and in the south winds of the east.

The storms, in the opposite direction of the clock.

Notice that in this area there are winds from the west,

and here are the winds from the east.

Therefore, this is a kind of still photography,

because this is going to move.

It will not be as simple as this,

because it is a still photograph of what the world is like.

And you also understand the climates of the earth.

Note that if you catch the 30th parallel, you put your finger on it,

and you follow it, you will find that all the deserts of the world are aligned

in the 30 degrees of north latitude, and almost in the 30 degrees of south latitude.

Almost, because in the southern hemisphere,

as there is less land, it is harder to see them.

And we will see that the storms here are a daily evolution,

Storms that appear and disappear every day.

Here are also the areas of hurricanes in the line of the

zero degrees of latitude.

While the poles are basically the deserts,

although it does not seem, in the poles almost never snows, almost never rains.

Here is an area of great aridity.

And it is because this is basically an anticyclonic zone.

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