Climate and weather | Global air circulation | Grade 12 Geography INTRODUCTION |Thundereduc|

Summary

The video script delves into the fundamental differences between climate and weather, emphasizing that climate represents a long-term atmospheric pattern, while weather is a short-term state of the atmosphere at a specific time and place. It explains that to define a climate region, such as tropical, savannah, or Mediterranean, one must collect and analyze weather data over an extended period, often decades. The script also explores the concepts of high and low pressure systems, their effects on weather, and how they are represented on weather maps. High pressure is associated with stable, cool conditions and limited rainfall, while low pressure brings unstable weather, often with rainfall. The movement of air in these systems is described, with high pressure causing air to diverge and low pressure leading to air convergence. The script concludes with a discussion on atmospheric pressure, its measurement in hectopascals, and its role in shaping weather patterns.

Takeaways

• 🌍 **Climate vs. Weather**: Climate is a long-term average of weather conditions in a region, while weather is the short-term state of the atmosphere at a specific time and place.
• ☀️ **Weather Description**: Weather includes conditions like sunny, windy, or rainy days, which describe the atmosphere's state at a particular moment.
• 📈 **Climate Data Collection**: To define climate, data is collected over a long period, typically 20-35 years, to understand the average weather patterns of a region.
• 🌬️ **Air Pressure Systems**: The global air pressure systems consist of high and low-pressure systems, which significantly influence weather conditions.
• ⬇️ **High Pressure**: High pressure is characterized by descending, stable air, leading to clear skies and limited rainfall, with air rotating anti-clockwise in the Southern Hemisphere.
• ⬆️ **Low Pressure**: Low pressure involves ascending, unstable air, often resulting in cloud formation and rainfall, with air rotating clockwise in the Southern Hemisphere.
• 🌀 **Air Movement**: Air converges at low-pressure areas and diverges from high-pressure areas, influencing the movement of weather systems.
• 🌡️ **Temperature and Pressure**: Cold air associated with high pressure exerts more force on the Earth's surface, while warm air rising in low-pressure areas results in less pressure.
• 🌤️ **Isobars and Weather Patterns**: Isobars on weather maps indicate areas of equal atmospheric pressure; their shape and spacing can suggest weather conditions such as clear skies or storms.
• 🌧️ **Cumulonimbus Clouds**: These clouds, associated with low-pressure systems, are responsible for heavy rainfall due to the rising and condensing of moist, warm air.
• 📊 **Atmospheric Pressure Measurement**: Atmospheric pressure is measured in hectopascals (hPa) or millibars (mb) using a barometer, reflecting the force exerted by air on the Earth's surface.

Q & A

What is the main difference between climate and weather?

Climate refers to the long-term atmospheric conditions of a region, while weather describes the short-term conditions of the atmosphere at a specific time and place.

How long does it typically take to collect information about weather to form a climate?

It usually takes about 20 to 35 years of daily weather data collection to form a climate.

What are the two main types of air pressure systems mentioned in the script?

The two main types of air pressure systems are high pressure and low pressure.

How does the direction of rotation differ between high and low pressure systems in the southern hemisphere?

In the southern hemisphere, high pressure systems rotate clockwise, while low pressure systems rotate counterclockwise.

What causes air to rise in a low pressure system?

During summer periods, the Earth's surface is heated by the sun, causing the air to expand and become unstable, which leads to rising air in a low pressure system.

What is the general weather condition associated with a high pressure system?

High pressure systems are associated with stable weather conditions, limited or no rainfall, and very cold conditions.

How do the shapes of isobars differ between high and low pressure systems?

In high pressure systems, isobars form an oval shape, while in low pressure systems, they form a circular shape.

What type of cloud cover is typically associated with heavy rainfall?

Overcast clouds, specifically cumulonimbus clouds, are typically associated with heavy rainfall.

What is atmospheric pressure and how is it measured?

Atmospheric pressure is the force that air exerts on the Earth's surface. It is measured using a barometer in units called hectopascals (hPa) or millibars (mb).

What happens to the air in a high pressure system?

In a high pressure system, the air descends, leading to clear and dry conditions with skies that are typically clear.

What is the relationship between the rising warm air and the formation of rainfall in a low pressure system?

The rising warm air, which is moist and light, rises and cools in the upper atmosphere, leading to condensation and the formation of clouds, which results in rainfall.

How does the direction of air movement differ between converging and diverging air in the context of pressure systems?

In a low pressure system, air converges or moves towards the center to fill the vacuum left by the rising warm air. In contrast, in a high pressure system, air diverges or moves away from the center due to the descending cool air.

Outlines

00:00

🌍 Understanding the Difference Between Climate and Weather

The first paragraph introduces the distinction between climate and weather. It emphasizes that climate encompasses a broader section, while weather is a smaller part of it. Weather is defined as the state of the atmosphere at a specific time and place, characterized by conditions such as sunny, windy, or rainy days. To form a climatic region, weather data is collected over an extended period, typically 20 to 35 years. The atmospheric conditions of a place over a long period define the climate, which can be tropical, savannah, Mediterranean, or equatorial. The paragraph also explains the concept of air pressure systems, including high and low pressure, and their characteristics in terms of direction of rotation and the resulting weather conditions.

05:02

🌦️ The Dynamics of High and Low Pressure Systems

The second paragraph delves into the dynamics of high and low pressure systems, explaining how they affect weather conditions. High pressure is associated with descending, stable air, resulting in limited rainfall and colder conditions. In contrast, low pressure involves ascending, warm, and moist air, leading to unstable weather, cloud formation, and rainfall. The behavior of air in these systems is influenced by temperature variations, with warm air rising and cold air sinking. The paragraph also discusses the convergence of air in low-pressure areas and the divergence in high-pressure areas. It further explains the visual representation of these systems on weather maps through isobars, which show the shape and direction of air movement, and how they correspond to different weather patterns and seasons.

10:02

📜 Atmospheric Pressure and Its Measurement

The third paragraph focuses on atmospheric pressure, which is the force exerted by air on the Earth's surface. It differentiates between high and low pressure in terms of the force exerted, with high pressure resulting from cold, descending air and low pressure from warm, ascending air. The measurement of atmospheric pressure is typically done using a barometer and is expressed in hectopascals (hPa) or millibars (mb). The paragraph also touches on the concept of global air saturation and how it relates to the overall understanding of weather patterns and climate.

Keywords

💡Climate

Climate refers to the long-term atmospheric conditions of a region, typically measured over a period of 20 to 30 years. It encompasses various elements such as temperature, precipitation, and wind patterns. In the video, climate is contrasted with weather to emphasize that climate is a broader and more enduring concept, representing the average weather conditions of an area over an extended period.

💡Weather

Weather is the state of the atmosphere at a specific time and place, including conditions like temperature, humidity, precipitation, and wind. It is a short-term phenomenon, describing what the atmosphere is doing at any given moment. The video script uses weather as an example to explain the immediate conditions, such as a sunny, windy, or rainy day.

💡High Pressure

High pressure in meteorology is a region where the atmosphere is descending, resulting in stable weather conditions with limited rainfall and cold temperatures. The video explains that high pressure is associated with clear skies and dry conditions, and it is identified by the anti-clockwise rotation of air in the Southern Hemisphere.

💡Low Pressure

Low pressure is an area where the atmosphere is ascending, leading to unstable weather conditions that often include rainfall. It is characterized by converging air and the formation of clouds, which is why low-pressure systems are typically associated with rainy weather. The video script mentions that low pressure is marked by a clockwise rotation of air in the Southern Hemisphere.

💡Air Pressure Systems

Air pressure systems are the global atmospheric circulation patterns that include high and low-pressure areas. These systems are crucial in determining weather and climate as they influence the movement of air masses and the development of weather fronts. The video discusses how these systems are categorized into high and low pressure, each with distinct characteristics and weather implications.

💡Isobars

Isobars are lines on a weather map that connect points of equal atmospheric pressure. They are used to visualize the distribution of high and low-pressure systems. The video script explains that in high-pressure areas, isobars form an oval shape, indicating stable and clear weather conditions, while in low-pressure areas, they form a circular shape, indicating unstable weather and potential rainfall.

💡Atmospheric Pressure

Atmospheric pressure is the force exerted by the weight of the air above the Earth's surface. It is measured in units such as hectopascals (hPa) or millibars (mb). The video script clarifies that high pressure is associated with descending cold air and a greater force exerted on the Earth's surface, whereas low pressure is linked to ascending warm air and less pressure.

💡Cumulonimbus Clouds

Cumulonimbus clouds are large, towering clouds associated with unstable weather conditions and heavy rainfall. They form due to the rising of warm, moist air which cools and condenses at higher altitudes. The video script mentions these clouds in the context of low-pressure systems, explaining that they are responsible for the formation of rainfall.

💡Global Air Saturation

Global air saturation refers to the distribution of air pressure systems around the world. The video script touches on this concept to explain how different air pressure systems, such as high and low pressure, affect weather patterns globally. It is a broader concept that encompasses the various pressure systems and their interactions.

💡Barometer

A barometer is an instrument used to measure atmospheric pressure. It is essential for predicting weather changes and is mentioned in the video script as a tool for measuring atmospheric pressure in units like hectopascals or millibars. Understanding changes in atmospheric pressure as indicated by a barometer is crucial for interpreting weather patterns and climate.

💡Ridge

A ridge in meteorology is an elongated area of high pressure. It is formed when two high-pressure cells merge, leading to a region with particularly stable weather conditions. The video script discusses ridges in the context of isobars, noting that when high-pressure cells are elongated, they result in a ridge, which is associated with clear and dry weather.

Highlights

Climate and weather are distinct concepts; climate represents a larger section, while weather is a smaller part of climate.

Weather is defined as the state of the atmosphere at a specific time and place, including conditions like sunny, windy, or rainy days.

Climate is the long-term atmospheric condition of a place, requiring data collection over 20 to 35 years to form climatic regions.

Different climatic regions, such as tropical, savannah, Mediterranean, and equatorial climates, are identified by collecting various weather elements over time.

Air pressure systems, including high and low pressure, are crucial for understanding global air saturation and weather patterns.

High pressure is characterized by descending, stable air with limited rainfall and cold conditions, rotating anti-clockwise in the southern hemisphere.

Low pressure involves ascending, unstable air with rainfall and convergence, rotating clockwise in the southern hemisphere.

During summer, the Earth's surface heats up, causing the air to expand and rise, leading to low pressure and potential rainfall.

High pressure is associated with clear skies and dry conditions, while low pressure is linked to cloud formation and rainfall.

Isobars in high pressure form an oval shape, indicating a ridge, whereas in low pressure, they form a circular shape, indicating a cyclone.

Atmospheric pressure is the force exerted by air on the Earth's surface, with cold air creating high pressure and warm air creating low pressure.

A barometer is used to measure atmospheric pressure in units of hectopascals (hPa) or millibars (mb).

Cumulonimbus clouds, associated with low pressure, are responsible for heavy rainfall due to the rising moist air and the release of latent heat.

Isobars around low pressure areas decrease towards the center, indicating rising warm air and potential for unstable weather conditions.

Understanding the difference between clockwise and anti-clockwise rotation is essential for distinguishing between high and low pressure systems.

Synoptic maps or weather maps are used to depict pressure systems, isobar patterns, and their effects on weather conditions.

The shape and movement of isobars provide insights into the weather conditions, such as clear skies in high pressure and potential rainfall in low pressure.

Global air saturation involves the interaction of various pressure systems and their effects on the Earth's climate and weather.

Transcripts

[Music]

today we are going to look at climate

and weather

and the topic we must understand is a

very big difference between climate

and weather

in this case

we must understand that climate

is a very big section and weather is a

smaller section of climate we already

see that the weather

tells us or it gives us

the climatic regions

so we need to understand that what is

weather

whether in this case is the state of the

atmosphere at a particular point

at a specific time

just like it is here

we look at it

at the smallest period of time

for example when we talk about whether

it's going to give us aspects like um

the day is sunny

the day is windy

the day is raining

all those ones are specifically

explaining

the weather state

of a particular place

at a specific time

it cannot be throughout rainy the whole

year or the whole month

so that's why we say it's a state of

atmosphere at a particular point at a

specific time

so in this case mythologies to collect

the information about whether

for the war for a very big period of

time say

20 to 25 years to 35 years

so that state of weather that is

collected on daily basis

is the one that is compiled to form up

the climatic regions there are for what

is climate

climate is the atmospheric condition of

a place measured for a very long period

of time so for the climate to be

recognized that this area is

experiencing um

a tropical climate it is experiencing a

savannah climate it's experiencing a

mediterranean climate or equatorial

climate we must focus on very many

aspects of weather all the elements of

weather must be collected for a very

long period of time such that we can

come up with the climatic regions that's

why it is a region that you look at and

you say this area is experiencing

savannah this area is

experiencing mediterranean climate this

area is experiencing equatorial all

right so

in that case we need to know that the

world or the group has got different air

pressure systems

which is basically under what you call

the global air saturation

in this case we have basically two

pressure systems or pressure systems and

these include the high pressure and the

low pressure first of all we need to

understand what's the difference between

these two you have been hearing about

the high pressure you've been hearing

about a low pressure it's not a mere

saying that's a low pressure or high

pressure we look at the conditions that

are experienced in the press to say this

place is experiencing a low pressure or

a high pressure

this is the two diagrams are giving a

difference

when you look at

this diagram here this diagram here is

showing the high pressure

how do we recognize the high pressure

high pressure a is descending

when you look at it it is descending but

it is descending as it is rotating in

that anti-clockwise

direction

so it rotates anti-clockwise

descending

now in this case as it descends it

simply means that we shall have a stable

climatic condition in the atmosphere

with no all limited rainfall

very cold conditions

and that is going to be explaining

what the high pressure we also have this

diagram on this other side that is

depicting a low pressure and when you

look at it a is rotating clockwise so

when you look at it you can see

clockwise you can notice here that this

clockwise

movement is only evident in

the southern hemisphere

and this one is also

evident in the southern hemisphere so in

the northern hemisphere it is going to

be the reverse the high pressure is

going to be clockwise the low pressure

is going to be

anti-clockwise but in this case these

two diagrams are depicting the southern

hemisphere so when you see here we say

that a here is ascending it is rising as

it is rising it is in the in that

clockwise

direction

so what up what causes this to happen

you must know that during um let me say

during the summer periods

the earthy surface is overheated by the

sun so

the earth the the surface of the earth

is heated by the sun so the air on the

earth's surface expands and it becomes

unstable that results it into rising up

in the upper atmosphere so the moist

air

which is lighter

rises up in the up in the upper

atmosphere condensing to form clouds

that will result into rainfall that's

why we say when you look at the low

pressure we say it experiences unstable

weather conditions

that is a low pressure so here is a high

pressure so in other words

with a low at a low pressure we must

know that air must converge at a low

pressure why because as air moves from a

high pressure it comes to a low pressure

to fill the vacuum that has been left by

the rising warm a that's why in a low

pressure a converges in the high

pressure a diverges it moves from a high

pressure to a low pressure then here it

is moving from a low pressure somewhere

to a high pressure so to a high pressure

a is diverging

as air diverges it diverges because

there is a descending chord a that is

going to push this a away from the high

pressure but within here a is converging

as there is a rising room a that is

supposed that results into air to move

from a different direction to come and

feel the vacuum that has been left by

the rising warm air so those are the two

aspects of the low pressure and the high

pressure so we must note that low

pressure has got ascending um ascending

air it has got unstable weather

conditions it always falls it is always

followed with a

formation of rainfall and also

convergence over

a into a low pressure when you look at

the high pressure there is a

descending cold air and this cold air

results into high pressure on the

surface of the earth there is divergence

there is a stable weather condition

limited or no rainfall at all that is

high pressure so in this case how do we

look at the shape of the isobars when

you look at the isobars in the high

pressure isobars in the high pressure

they form the oval shape

this oval shape results into unelongated

high pressure so when the two high

pressure cells are elongated it results

into a ridge

in the same case i've talked about the

air sinking so a is sinking or

descending

the air saturation is clockwise in the

southern hemisphere the skies are clear

and dry conditions

isobus increase towards the center

actually all these conditions that are

indicated here are depicting uh the

winter seasons you'll find that during

winter it is descending air air is

rotating uh or saturates in the

anti-clockwise direction in the southern

hemisphere clear skies the dry the

conditions are very dry and so on and so

forth that is a high pressure we move

forward to a low pressure

when we go to a low pressure the low

pressure iso has formed that round shape

we call it the circular shape

as

it is rotating towards the center it

forms this circular shape

and then

this shape in the circular shape is

depicted here

okay

then when you look at that a rises at

the center

a rises at center it's just known it's

not only any air that is rising it's

basically the warm air that is rising

and the reason why it is in position to

rise it's because this air is light it's

moist therefore it is in position to

rise as it becomes unstable on the

earthy surface we look at the second one

i say air saturates in a clockwise

direction we can also see on this

diagram this is clockwise if you cannot

see it clearly or if you can't observe

or you can't differentiate between

clockwise and anti-clockwise you can

look at a waist watch when you look at

the whiskers you'll see that it rotates

this other side like a clock rotates

this other side so that is clockwise so

the opposite becomes anti-clockwise

okay

we go back to this and say clouds here

cloud cover and rainfall form

which kind of cloud cover do you

experience in this in this scenario the

cloud the cloud cover is going to be

that overcast clouds are normally

referred to as the cumulonimbus clouds

that is responsible for the heavy

rainfall why does it form these kinds of

clouds will form for the effect because

of the fact that there is a rising moist

a that air has got heat embedded which

you call the kinetic heat or the kinetic

energy so as it rises in the upper

atmosphere it condenses to form clouds

after losing that latent heat that

results into the formation of clouds

hence forming rainfall in the same case

we shall see that isobars decrease

towards the center

how do you look at this we see that when

you look at a low pressure

when you look at a low pressure this the

isobars are going to be drawn

somewhere here

the isobars are going to be drawn

somewhere here and you'll find that as

you move away from the center it is

increasing as you move towards the

center it is decreasing okay those are

the kind of the isobars we are talking

about and that is mainly depicted

synoptic maps or weather maps in this

case

we need to understand we are talking

about pressure we are talking about

isobus but what is uh what is pressure

what is atmospheric pressure first of

all atmospheric pressure is explained as

the force that air exerts onto the

earthy surface

as

cold air descends it exerts too much

pressure onto the earthy surface and

when it exerts that too much pressure

onto the earthy surface that's why we

say it is a high pressure

on the low pressure when you look at it

the warm air is rising that means it is

leaving the earthy surface with less

pressure that's why we say it's a low

pressure when it is

hot so atmospheric pressure is basically

measured

with a barometer

in what you call hectopascal or

meal bus so if you don't find the one

hectare pascal which is abbreviated as

hp

as we find it as a mil bus mb

that is um

so we move forward to understanding this

global a saturation