SCI4-Q4 LESSON

1. IN THE HEAT OF THE SUN
By Ms. Elaine L. Villaluz

2. BREEZE
a light and pleasant wind
SPECIFIC HEAT
The amount of heat needed before a material changes its temperature
Water has a large capacity to absorb heat, as
described previously. This means that water needs more heat before it changes its
temperature.
As solids, sand and soil heat up faster than water because they need lesser heat to raise
their temperature.

3. The soil and sand are warmer than the water, the air above the soil
becomes warmer too. One characteristic of warm air is that it rises. It has so
much kinetic or vibrational energy that it seeks out places where it can go.
As the air above the warm Earth heats up, it will rise and expand. When air
expands, it then cools.
AGHAMAZING!
Take your hand and place it around 5 to 10
centimeters away from your mouth. Breathe
on your hand as if you are checking if you
have already brushed your teeth, with a
breathy “Ha!” You will feel with your palm
that your breath is warm. Now, pucker your
lips and blow air on your palm. You will now
feel that your breath is cooler.

4. DYKW?
This is because when you pucker your lips, the
opening of your mouth spreads the air as it leaves,
whereas when you are checking your breath, the air
leaves your mouth like a solid column.

5. During the day, the land and the ocean all absorb the energy from the
sun. However, it will take the water a longer time to heat up because of its high
specific heat. The warm air will then be coming from the land. When warm air
rises, it spreads and cools down. Then it begins to sink on the ocean (near the
ocean surface).
The cooled air will stay over the water. Then the wind will blow the cool, dense
air to the land. The cooler air will then be warmed by the land, and the cycle
begins again
This is a SEA BREEZE - a convection current where the cool
air from the sea goes into the land.

6. In the evening, the sun disappears, and the heat that was transferred
into the ground and the water is now released. The ground releases heat
faster than the water, making the ground cooler than the water. The air above
the water heats up and rises. Once it rises in the air, it begins to cool.
The cooled air begins to sink over the ground. The wind will then blow the
cooled air toward the water. Once the cooler air reaches the water, it warms
up and the cycle continues.
This is a LAND BREEZE - the convection current moves from
the land onto the water. is kind of localized convection current
often happens near lakes and bays.

7. MONSOONS
Seasonally changing winds caused by convection currents that bring with them
additional rain or dry cold air depending on where they are coming from. .
The word “monsoon” comes from the Arabic term mawsim, which means
“seasons.” Countries such as India and the US have their own monsoons. In
the Philippines, we have two
Southwest monsoon,
Northeast monsoon,

8. So-called because the convection
current brings humid air from the
Indian Ocean and moves from the
southwest.
Locally known as hanging habagat
and happens during June to October.
During this season, strong winds and
storms are experienced by the regions
near the West Philippine Sea or the
western side of the country. If there is
enough water vapor with the habagat,
the warm air rises.
Southwest monsoon vs. Northeast Monsoon
Also known as hanging amihan. A
convection current coming from
Siberia and China that blows cooled
air over the entire Southeast Asian
region.
This happens from November to May,
which corresponds with the cool dry
and warm dry seasons of the
Philippines during Christmas and
summer, respectively. There are
hardly any strong storms during this
season, and there are only feathery
cirrus clouds in the sky.

10. PREVAILING SURFACE WINDS
Wind movements between certain
latitudes. These prevailing winds move
over the surface of Earth from a
latitude where the atmospheric
pressure is higher toward the place
where the atmospheric pressure is
lower.

11. ATMOSPHERIC PRESSURE
The force applied by the weight of the atmosphere over a surface area. The
place where there is a higher atmospheric pressure would push the
atmosphere and form the prevailing winds toward the area where there is
lower pressure.
As Earth rotates, the resulting atmospheric movement begins to curve toward
the lower atmospheric pressure.

12. In the place where the atmospheric pressure is highest or lowest,
there is hardly any wind movement.
When the atmospheric pressure is low such as at the equator, the sun
evaporates the water really fast, so the hot air moves directly upward, and
therefore, there is no wind. Sailors call this calm region of hot air the
doldrums. The doldrums can sometimes last for days or even weeks, so
sailboats are stuck in a place where there is no wind.
In the case of high-pressure regions such as those at the horse latitudes, the
high pressure is due to the cooler air that sinks downward. These are also
regions of clear skies because there is hardly any warm water vapor in the air
to form clouds.

13. Where do you specifically see these areas of high and
low atmospheric pressure?
The latitudes of low pressure are in places such as the intertropical
convergence zone (ITCZ), located near the equator, and the polar fronts,
located at 60° latitudes (north and south). These are also called
convergence zones because the winds go toward these latitudes.
The wind is pushed by the high-pressure latitudes toward the low-pressure
latitudes. These high-pressure latitudes are also called the horse
latitudes. These are located at 30°N and at 30°S. It is also called a
divergence zone because the winds move away from the horse latitudes.
As a region of high atmospheric pressure, the cooler air is pushed toward the
warmer areas.

14. TRADE WINDS
Also known as easterlies are permanent east-to-west prevailing winds that
flow in the Earth's equatorial region.
WESTERLIES
the prevailing winds in the middle latitudes blowing from the subtropical
high pressure toward the poles.
Polar easterlies: They are dry
and cold prevailing winds that blow
from the east. They emanate from
the polar highs, areas of high
pressure around the North and
South Poles. Polar easterlies flow to
low-pressure areas in sub-polar
regions.
Trade winds: They are the
powerful prevailing winds that blow
from the east across the tropics.
Trade winds are also known as
tropical easterlies. They start blowing
from the sub-tropical high-pressure
areas towards the equatorial low-
pressure belt.
EASTERLIES - An easterly wind is a wind that blows from the east.

15. CONVECTION CELLS
All of these prevailing surface winds are moving across the curved surface of
Earth, and that is why they do not move in lines parallel to the latitudes but slant
across the surface of Earth. What powers these winds are the movement of
convection currents that goes up and down, away from the surface of Earth and
up into the atmosphere. There are three major convection cells that are confined
between the ITCZ, horse latitude, and polar front.
• Hadley Cells
• Ferrel Cells
• Polar

17. Ferrel cell is convection cell is named after the American meteorologist William
Ferrel (1817–1891), who described how this convection cycle works. Located
between the horse latitude and the polar front, it powers the warm westerlies.
Polar cell is a convection current that propels the easterlies. The atmosphere
over the relatively warmer polar front rises and expands as it moves toward the
poles. The north and south poles are high-pressure areas because they are so cold,
where it descends and pushes the cool air toward the polar front where it is heated
and the cycle continues.
Hadley Cells are the low-latitude overturning circulations that have air rising
at the equator and air sinking at roughly 30° latitude. They are responsible for the
trade winds in the Tropics and control low-latitude weather patterns.
The term is named after the lawyer and amateur meteorologist George Hadley
(1685–1768)

18. These convection cells are mirrored in the
southern hemisphere. As Earth revolves
around the sun, its tilt as it rotates on its
axis means that different parts of Earth
are exposed to more heat. As a result, the
ITCZ, horse latitudes, and polar fronts
would adjust and move. This is why
monsoons occur.
As the position of the ITCZ would change
over the months, the monsoons would
also change with it.

19. Human Activities that affect the Winds
The main culprit in the unnatural changes in the prevailing winds and
convection cells is global warming. The most measurable changes are the
slowing down of the trade winds and the changes in the direction of the
westerlies to a more southern direction. e changes in the polar winds are not
yet known because there is not much information about the polar winds, due
to the fact that there aren’t many that inhabit the poles.
The impact of the slowing movement of the trade winds would have been
more felt if there were more ships that use the wind. However, the slowing
down of the trade winds end up affecting the ocean ecosystem.

20. The root of all these changes are the human activities that contribute to global
warming. These include the increase of greenhouse gases that are changing
the temperature of the atmosphere. It was discussed previously that these
gases are primarily caused by carbon emissions, release of methane and
nitrous oxide, and buildup of aerosols.