This content explains the fundamental concepts of energy, heat, and temperature, and how these principles, particularly heat transfer mechanisms, are crucial for understanding atmospheric processes and weather phenomena.
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in this video we're gonna talk about
heat transfer we're gonna talk about
heat energy and we're gonna talk about
temperature and this is very important
in beginning to understand how weather
works so when we talk about energy what
is energy
well energy is the capacity to do work
so whether it's heating of the Earth's
surface or changing water in different
phases it requires energy to do so so we
need to discuss energy before we can
talk about how weather actually works
because this would be the foundation to
how weather actually occurs in our
atmosphere so when we talk about energy
we talk about two forms of energy
kinetic energy and potential energy
kinetic energy is energy that is in
motion or already in motion so think
about a car a car is driving therefore
it's in motion and that is what kinetic
energy is potential energy is energy
that is possessed by system that has the
potential to be kinetic energy down the
road so if we think about a car for an
example but a car is parked it's not
moving if it's not moving it's not doing
any work therefore not giving off any
energy however we know that cars can and
are in motion and so when we drive our
car therefore it is in motion we are
doing work because we are traveling from
one place to the other
therefore it is then kinetic energy so
that's the difference between kinetic
energy and potential energy but since
we're talking about meteorology we want
to talk about heat energy because that's
what temperature is when we talk about
temperature what in the normal world we
talk about how hot or cold the air is
outside boy in the scientific community
what temperature is it's the measure of
the average kinetic energy of all the
constituents of air molecules so all of
the nitrogen molecules all of the oxygen
molecules all of the argon air molecules
so all of those molecules moving is
kinetic energy it's heat
and that's what we relate to as
temperature so the faster that these
molecules are moving the higher their
kinetic energy the higher their kinetic
energy the higher the heat energy and
therefore we say that the warmer the air
is and so when these molecules are not
very excited and they're moving slowly
we say that the kinetic energy is less
therefore the heat energy is less and
therefore the temperature is cooler and
so when we talk about heat we can
actually break heat down into three
different sub parts we talk about latent
heat specific heat and sensible heat and
this becomes very important in the
physics of our atmosphere because this
is how water plays a role and
temperature plays a role in our
atmosphere and we're going to discuss
this a little bit in greater detail in
week four but to define these terms when
we talk about specific heat we're
talking about the amount of energy that
is required to change a unit of mass by
one degree so in this case we're talking
about water here and so how much energy
is required to raise the temperature of
water by one degree and so that is what
specific he is you can easily remember
that by saying specific heat one degree
Celsius that's a specific number so
specific heat the amount of energy
needed to raise waters temperature by
one degree
now latent heat is also extremely
important in our atmosphere now lady he
is the energy that is required to change
the state of water in this case since
we're talking about meteorology how much
energy is required to change water from
a gas to a liquid a liquid to a solid or
a liquid to a gas whatever combination
you want to make that is what latent
heat is and latent heat is going to be
very important and we're gonna discuss
it in greater detail again when we get
to week four
now sensible heat sensible heat is the
energy required to change the
temperature of a substance but with
the phase-change so sensible heat and
specific key are essentially the same
thing except specific heat is more
specific as we're talking about how much
energy was required to raise the
temperature of water by one degree now
when we talk about heat transfer
throughout the earth how is heat
transferred from one entity to the other
so when we talk about heat flow we talk
about things going from hot to cold and
so heat flows via three different ways
either by conduction convection or
radiation now the earth receives all
three now starting with conduction
conduction is the transfer of heat
through matter by molecular motion so
this would be an example of you're
cooking and you touch a hot pan and you
don't realize it and you burn yourself
slightly that would be an example of
heat transfer by conduction there was
some source of heat that heated the pan
or the pot or whatever you're cooking
with you touched the pot the pot was hot
because of molecular transfer the matter
that or the molecules that make up the
matter of the pot was heated you touched
the pot that was hot you got burned it
transferred heat to your hand your brain
told you hey that's hot and that is how
heat is transferred that's what
conduction is convection is the transfer
of heat by mass motion or via
circulation so if you've ever seen water
boil before that is conduction you have
water or air that is heated either at
the bottom of the pan or the surface of
the earth is heated by the Sun hot air
rises or hot water rises and then cold
air comes down to replace the hot air
that's rising so when we look at boiling
water this is exactly what we see and so
here you notice that the hot water rises
and in the cold water that was at the
top of the pot comes down to replace the
water that has now risen to the top of
the pot okay and so this is what that
bubbling motion does and this is
actually what happens in our atmosphere
well we talk about radiation this is how
the whole machine works and so we know
that the earth receives its energy via
the Sun so we're talking about
electromagnetic radiation
aka we're just talking about solar
energy so solar radiation and that is
the transfer of electromagnetic energy
via electromagnetic waves and that's
what the Sun does the Sun shines its
solar energy reaches the surface of the
earth and the earth heats either by
conduction and/or convection so all
three heat transfers occur on the earth
and it's actually what makes weather
happen so when we break it down
radiation if you're talking about you
know cooking with an open fire radiation
right that's the heat that you feel from
fire and if you've ever had a bonfire
before you got close to that fire
you can feel how hot that fire is well
those are the electromagnetic waves that
are traveling towards you that give off
heat and so that's what radiational heat
is convection would be water boiling so
here in this diagram you see that the
hot water is at the bottom of the pot it
boils it bubbles hot water or hot air
works the same way Rises and then cold
water at the top row cold air from
higher up in the surface comes down and
replaces the hot air or hot water that
has now risen so this is what convection
is it's just one big giant loop and then
conduction right that would be the
transfer of heat through matter and so
when we actually look at it in a
meteorological terms the Sun comes out
and heats the surface of the earth now
remember that the sun's rays do not
directly heat air molecules all air
molecules are transparent so how does
the air actually get warmed while the
Sun comes out and heats the surface of
the earth the surface of the earth is
there heated and the air that
lies right above the surface of the
earth is therefore heated by conduction
because it's in close contact with the
ground that air that sits right above
the surface of the earth becomes hotter
than the surrounding environment hot air
rises if you've ever watched a hot air
balloon hot air balloons work because
hot air rises in cold air sinks same
thing with water warm water rises to the
top and cold water sinks so in this
diagram over here on the left in Part A
you see that the Sun heats the surface
of the earth the surface of the earth
heats the air that lies right above the
surface of the earth and those air
parcels become warmer than the
surrounding environment and they rise so
then what happens is that those air
parcels will rise to a certain level
become saturated and form a cloud so
when air is rising cool air has to come
down to replace it and this is what's
known as convection so whenever you see
clouds occur this is what happens and
this is what we call convection now
we're going to talk more about
convection and more about how clouds
form later on in the semester but for
right now know that these are the three
ways that heat is transferred throughout
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