Philippines Grade 6 Science Chapter 10

WEATHER, SEASON AND CLIMATE

CHAPER 10

WEATHER, SEASON AND CLIMATE

You come to know and predict the weather by looking at the sun, feeling the temperature of air and watching the clouds. You also observe the movement of things around you to determine wind direction. But more often than not, your predictions based on these observations are not accurate or reliable.

Meteorologists use different instruments to collect data about these weather elements. Weather satellites nor orbit the earth to gather better and accurate observations about the air above the earth. Different weather stations all over the country or worldwide analyze and interpret these observations. PAGASA then makes the official weather forecasts which are broadcasted daily nationwide.

• In this chapter, you will learn more about the weather and climate of your place. Are weather and climate the same? How are they alike or different? What factors affect climate? What type of climate prevails in your place? Why does the Philippines have two types of seasons only? What factors affect seasons?

WEATHER VERSUS CLIMATELESSON 1

You have learned that weather describes the condition of the air or atmosphere around you. This condition exists for a very short period of time. When you say today is sunny or predict that tomorrow will be rainy, what are you talking about? Are weather and climate the same?

A certain place may be cold and rainy on a particular day. But this place may have a dry, warm sunny climate. This is because weather and climate are not the same.

Weather comes from the temporary condition of the atmosphere. Climate is the total weather in the region over a long period of time. Climate is the combination of temperature, moisture, wind and sunshine at a place over a period of years. The study of climate is known as climatology. The scientists who specialize in the study of climate are called climatologists. Climatologists learn about the climate of a place by studying its weather from season to season and year to year.

Temperature, precipitation (moisture that falls to the ground), humidity (moisture present in the air), cloudiness, air pressure and wind are factors that determine the weather and climate of a place.

REMEMBERING SCIENCE FACTS

• Weather is the condition of the atmosphere everyday.

• Climate is the condition of the atmosphere over a long period of time.

REACHING OUT: YES OR NO1. Weather and climate both refer to the condition of the atmosphere.

2. Climate takes place everyday.

3. The weather and climate of a place may vary.

4. A climatologist may also be a meteorologist.

5. The total weather of a certain place over a year is called climate.

6. PAGASA issues a weather bulletin daily.

7. Weather is affected by temperature which is the amount of moisture present in the air.

8. The climate of a place varies from day to day.

9. Climatologists and meteorologists are scientists who specialize in the study of the conditions of the atmosphere.

10. Weather and climate are not the same.

FACTORS AFFECTING CLIMATELESSON 2

FACTORS AFFECTING CLIMATEWhere do you live? Is it hot

all year long in your place? What makes your place hot all year long while another place is cold? Why is one place a desert while another is a rainforest? Why do different regions experience different climates? What factors or climatic controls are responsible for the differences in climatic conditions from place to place?

LATITUDE

Your location on the earth’s surface in relation to the sun likewise affects the climate you have. Are you closer to the equator or to the poles of the earth? Where is the Philippines located?

The main factor that determines the climate of any place is its distance from the equator. This distance is measured in degrees of latitude; the equator is 0 degrees latitude. The equator is the imaginary line that divides the globe into two halves or hemispheres – the Northern Hemisphere and the Southern Hemisphere.

The Philippines is located close to the equator. At the equator, the sun is never very far from being directly overhead at noon. The sun’s rays hit the earth most directly at the equator. So these places are warm all year.

At sunrise and late afternoon, the rays of the sun are diagonal. The energy from the sun is much less these times of the day. But at noon, the sun is directly overhead. You get vertical rays this time so the heat is readily intense.

During the months of March, April and May, the Philippines receives vertical rays. You experience a hot climate or warm summer months. The North Pole and the South Pole do not get any sunlight at all for six months of the year. They have cold climates. In some places at the middle latitudes such as California and Japan, the sun is high or overhead during summer. These places have warm summers because they also have long daytime. At winter, the sun is low in the sky. These places receive diagonal rays; so, they have cold winters. They also have longer nights and shorter daytime.

ALTITUDE

The earth’s surface is very irregular. It is not flat throughout. There are some elevations of high places such as the mountains, plateaus and hills. Some places are wide and flat such as the plains. How does surface elevation or altitude affect climate?

Have you ever been to Baguio City and other mountainous places? Throughout the year, these places have a cool, comfortable climate, even during summer months. This is why Baguio City is the “summer capital of the Philippines”. Why is Baguio’s climate like this?

Baguio City is almost 2,300 feet above sea level. The altitude or elevation of the place affects its climate. Temperature becomes lower as the height above sea level goes higher. Temperature decreases as altitude increases. At high altitudes, the air does not absorb and hold as much heat; it is less dense. Climatologists have discovered that temperature drops about 2˚ Celsius for each 300 meters or 1,000 feet of altitude. Do you understand now why Baguio has that cool climate all year round?

At daytime, the sun warms the land and water surfaces on earth. Which surface heats faster? Which cools faster? What happens to the air around them?

Land surfaces warm up rapidly or faster when the air is warm. They also cool rapidly when the temperature becomes lower. But large bodies of water such as the oceans change temperature more slowly. Places near these bodies of water such as the sea coasts or islands have milder winters and cooler summers because of water surfaces nearby. Evaporation of moisture from the ocean’s surface releases heat.

Great streams of water moving in the oceans are called ocean currents. Some currents carry warm water to cool regions. Warm ocean currents flow from the tropical seas toward the polar regions.

Other ocean currents carry cool water to warm regions. These currents affect climate in many parts of the world.

WIND SYSTEMS

As you have learned, wind is moving air. It is air in motion. Wind is formed because of the unequal heating of the land and water forms on the earth’s surface. During the day, the land heats up faster than the bodies of water. Air above these land surfaces gets heated, becomes lighter and moves upward. It goes to the water forms. Cool air is more compact and heavy. So cold air sinks. It replaces the heated air over the land. There is continuous exchange of heated air rising and cold air sinking. This produces convection currents. Air close to the earth moves from regions where there is more pressure to regions where there is less pressure. This makes the breeze.

People living near oceans and lakes experience the breeze. There are two kinds of breeze – land breeze and sea breeze. During the day, warm air over the land rises and is replaced by the cool air over the water. This is called a sea breeze. During the night, the land becomes cooler than water. Warmer air over the water rises and is replaced by cooler air from the land. This is called a land breeze.

On large surfaces, continents heat and cool faster than oceans. A center of low pressure develops over the continent while high pressure develops over the adjacent ocean. These bring wind systems known as seasonal winds or monsoons. These wind systems affect climate because they carry heat and moisture.

The Philippines is affected by these following wind systems:

NORTHEAST MONSOON

From October to February, a high pressure area develops over Southern Siberia and India in winter because of the cold air over these places. This mass of cold air moves toward the Pacific Ocean. It reaches the Philippines from a northeasterly direction, thus, the name northeast monsoon. This monsoon brings cold mornings and heavy rainfall along the eastern coastal regions of the Philippines.

SOUTHWEST MONSOON

From June to September, the continent of Asia becomes warmer than the oceans nearby. A cold air mass develops over the Pacific Ocean. It moves toward the Asian continent from a southwest direction. Southwest monsoon brings heavy rainfall along the western coastal areas of the Philippines.

TRADE WINDS

These are the prevailing winds in the tropics. They are winds that blow from the same direction most of the time. These wind systems affect the Philippines whenever the monsoons weaken during the rest of the year.

• South Pacific Trades bring humid weather in the month of July.

• North Pacific Trades bring warm weather during the months of April and May.


• Latitude is the distance of a place from the equator.

• The equator is at 0˚ latitude. It is an imaginary line which divides the globe into Northern and Southern Hemispheres.

• Altitude is the elevation of a place above sea level. Temperature decreases as altitude increases.

• Ocean currents are streams of water moving in the oceans.

• Northeast monsoon, Southwest monsoon and trade winds are wind systems which affect the Philippine climate.

REACHING OUT: FILL IN THE BLANKS1. Great water moving in the oceans are called _________.

2. Winds which blow in the same direction most of the time are called ________.

3. Temperature decreases when _______ increases.

4. Scientists which specialize in the study of climate are called __________.

5. Seasonal winds which affect the climate are called _________.

6. The imaginary line which separates the globe into two hemispheres is the _______.

7. During night time, warm air over the water rises and is replaced by cold air from the land. This is called ________.

8. From June to September, heavy rainfall along the west coastal areas are brought by _________.

9. The distance of a place from the equator is called __________.

10. Air in motion is called ________.

EARTH’S MOVEMENT AFFECTS CLIMATELESSON 3

EARTH’S MOVEMENT AFFECTS CLIMATE

The earth rotates on its axis everyday. As it rotates, one side of it faces the sun and is completely lighted while the other side is in darkness. The axis is the imaginary line drawn from pole to pole which divides the globe into east and west. The earth’s axis is inclined. How does the rotation of the earth on its axis affect climate?

The amount of heat received from the sun affects the climate in a certain region. This depends on the kind of light rays the place receives and its length of daytime. The movements of the earth have something to do with these factors. The earth’s axis is inclined at 23 ½ degrees. Because of this, some parts of the earth receive vertical rays while other parts receive diagonal rays. Regions on earth that receive vertical rays have hot climate almost all year round. Those which receive diagonal rays have cooler climate.

The earth also revolves around the sun. It takes the earth 365 ¼ days to complete one revolution. As the earth revolves, its inclination changes. During some months, it is inclined toward the sun. Places on this side of the earth have hot season or summer. Those places which are tilted away from the sun have cold season or winter.

Daytime is measured from sunrise to sunset. Because the earth rotates, people in different places have different sunrise and sunset, too. During summer months, daytime is longer because the sun rises earlier and sets later than usual. So, you experience hot climate during these months. What months are these? During cold months, the sun rises much later and sets much earlier. Again, what months are these?

The counterclockwise movement of the earth causes the flow of air from the poles toward the equator. This affects the wind system of the world. The winds, instead of blowing straight north to south, are deflected or curved to the right in the northern hemisphere and to the left in the southern hemisphere. Heated air at the equator rises and creates a belt of low pressure around the equator. This is called doldrums. The earth has eight climate zones.


• The earth’s rotation and revolution affect the amount of heat and wind system. These are factors or climatic controls in different places on earth.

• The earth is inclined at 23 ½ degrees. Some places which receive vertical rays are warm all year round. The places which receive slanted rays are cooler.

REACHING OUT: LIST…

A. Two movements of the earth:

1:

2:

B. Wind systems which affect the Philippines:

3:

4:

5:

C. Factors that affect climate:

6:

7:

8:

9:

10:

CAUSES OF SEASONSLESSON 4

CAUSES OF SEASONS

What kinds of seasons does the Philippines have? What are the different seasons in other countries? What causes these different seasons? Is it possible for the Philippines to have these different seasons too?

The earth is constantly moving. It orbits the sun once each year and spins on its axis once every 24 hours. As the earth orbits the sun, the days change. The lengths of the day change and the temperatures change. These movements of the earth cause the seasons to change. Because the earth’s axis is tilted with regard to the earth’s orbit, each pole is turned toward the sun for part of the year and turned away from the sun the rest of the year.

The seasons north of the equator are always opposite of the seasons south of the equator. When it is summer in the North Hemisphere, the North Pole is turned toward the sun and it almost has continuous sunlight.

In other countries nearby, the sun shines longer everyday. The sunlight seems hotter than it does at other seasons. At the South Pole, however, it is winder and there is almost continuous night because it is turned away from the sun. Countries at the Southern Hemisphere have shorter days and the sun seems low in the sky.

But for countries at the equator, it is always summer; it is the same hot weather throughout the year. It receives the same amount of sunlight all year long – about 12 hours long for both day and night. In the tropics like the Philippines, there are only two distinct seasons; the dry and the rainy season. Dry season has more hot, humid days. The summer sun is higher in the sky and shines down more directly on the earth, making heat and light more concentrated. The days are longer, which gives the sun more time to heat the earth. During the rainy season, the Philippines has heavy rainfall and is frequently visited by typhoons.

During the earth’s revolution around the sun, temperate countries above and below the equator experience four seasons – winter, spring, summer and autumn or fall. The sun’s highest position in the sky (high noon) changes with the seasons. In the Northern Hemisphere, the spring equinox comes on March 21. Equinox means the length of the day equals the length of the night. As the earth moves, the sun seems to climb higher in the sky. The hours of daylight become longer everyday. The summer solstice comes about June 22. Solstice means “sun stand still.” At this point, the North Pole tilts directly toward the sun.

Again as the earth moves away from this point, the days gradually become shorter. Fall equinox happens on September 23 when the nights are as long as the days. Then, the North pole tilts away from the sun. The sun seems low in the sky at noon. Days are short and nights are long. Winter arrives with the winter solstice on December 22. In the Southern Hemisphere, the seasons are exactly opposite to those in the Northern Hemisphere. Can you tell the different seasons occurring there?


• As the earth revolves around the sun, the lengths of the days and temperature change. Seasons change too.

• In temperate countries, there are four seasons – spring, summer, fall and winter.

• At the equator, it is always summer. It receives the same amount of sunlight all year long.

• The Philippines has two seasons: the dry and wet season.

REACHING OUT: TRUE OR FALSE

1. In temperate countries, there are changes in seasons from spring, summer, fall and winter.

2. Solstice means equal days and equal nights.

3. It is always summer at the equator because it receives the same amount of sunlight the whole year round.

4. The revolution of the earth affects the lengths of the days and temperature on earth.

5. The seasons north of the equator are always opposite of the seasons south of the equator.

REACHING OUT: IDENTIFY THE WORD

1. This season in the Philippines has hot, humid days since the days are longer.

2. It means equal days and equal nights.

3. These countries are located above and below the equator.

4. At this time of the day, the sun is at its highest position in the sky.

5. This movement of the earth causes changes in season at different places of the earth.

TYPES OF CLIMATE IN THE PHILIPPINESLESSON 5

TYPES OF CLIMATE IN THE PHILIPPINES

Since the Philippines is at the Tropic of Cancer, it only experiences the wet and dry seasons. But is the climate the same in all parts of the country? What is the climate type in your place? Is it the same as the one in Luzon or Mindanao?

During the months of July, August and September, the Philippines usually has frequent rains. Strong typhoons also occur during these months. Recall the typhoons which have struck the country during previous years. Which month has the most class suspensions due to typhoons?

PAGASA issues the climate map of the Philippines. It is based on the temperature of air and the amount of rainfall. The Philippine climate is classified into four types:

Type 1 Two pronounced wet and dry seasons. Dry from November to April and wet the rest of the year.

Type 2 No dry season; with a very pronounced maximum rain period from November to January.

Type 3 Seasons are not very pronounced; relatively dry from November to April and wet during the rest of the year. No maximum rain period.

Type 4 Rainfall is more or less distributed throughout the year. There is no dry season and no pronounced maximum rain period.


• Climate types in the Philippines are based on temperature of air and the amount of rainfall.

CLIMATE AND YOULESSON 6

CLIMATE AND YOUExtremely high or low temperatures are uncomfortable. But it is difficult to

determine what is the best or ideal climate for human beings. Your comfort , well-being and activities are somewhat affected by climate in many ways.

Most people do not work as well in a hot, moist climate as in a cooler, drier climate. The kind of clothes you wear is also determined by climate. Less clothing is needed in a warm climate, but warm thick clothing for a cold climate gives protection against wind and cold. People differ in wearing special clothing for wind, sun, cold, rain and snow.

Observe the clothes worn in different climates.

People also have built houses mainly for shelter from the climatic elements. Some houses take advantage of sunlight, wind and other factors to obtain maximum comfort and protection. Sometimes, the sun and wind can be used to provide heat and power. Technology has made it possible for people to live and work comfortably in any kind of climate.

Climate also affects transportation. In polar climates, people often travel on skis are by snowmobile. In dense tropical forests, rivers are often the major highways. Climate also influences the agriculture or production of crops and animals. Wheat and potatoes grow well in cool climates; whereas banana and sugar cane thrive in warm, wet climates. Certain diseases are also more common in some climates. But young people usually adjust more easily to different climates than older people.


• Climate affects the lifestyle, clothing, transportation and even social activities of people in a certain region.

• The kind of agricultural products and animals which thrive in a region also depend upon climate.

FOR YOU TO REMEMBER

• Weather is the condition of the atmosphere everyday.

• Climate is the condition of the atmosphere over a long period of time.

• Latitude is the distance of a place from the equator.

• The equator is at 0˚ latitude. It is an imaginary line which divides the globe into Northern and Southern Hemispheres.

• Altitude is the elevation of a place above sea level. Temperature decreases as altitude increases.

• Ocean currents are streams of water moving in the oceans.

• Northeast monsoon, Southwest monsoon and trade winds are wind systems which affect the Philippine climate.

• The earth’s rotation and revolution affect the amount of heat and wind system. These are factors or climatic controls in different places on earth.

• The earth is inclined at 23 ½ degrees. Some places which receive vertical rays are warm all year round. The places which receive slanted rays are cooler.

• As the earth revolves around the sun, the lengths of the days and temperature change. Seasons change too.

• In temperate countries, there are four seasons – spring, summer, fall and winter.

• At the equator, it is always summer. It receives the same amount of sunlight all year long.

• The Philippines has two seasons: the dry and wet season.

• Climate types in the Philippines are based on temperature of air and the amount of rainfall.

• Climate affects the lifestyle, clothing, transportation and even social activities of people in a certain region.

• The kind of agricultural products and animals which thrive in a region also depend upon climate.

Education

Philippines Grade 6 Science Chapter 10