CHAPTER 19WEATHER AND CLIMATE

Weather satellites, computers, and other kinds of weather instrument provide accurate information about weather conditions.

Meteorologists are people who study the weather and use weather data to predict the weather.

Their forecasts help us plan our daily activities.

Guide Questions: 1.Have you ever wondered what the

weather will be on a certain day? 2.You experience weather (yes or no)

and why? 3.The typhoons is very strong? 4.Have you see a heavy typhoons?

WHAT DOES WEATHER MEAN?

Weather is the condition of the atmosphere at any given time and place.

The chief elements of weather are sunshine, temperature, air pressure, wind, humidity (moisture), clouds , and precipitation. All these elements change frequently.

Weather science is known as meteorology.

This term comes from two Greek words Meteoros meaning ‘high in the air’ Logos meaning ‘knowledge’

Meteorologists in all parts every hour of what the weather is where they are.

Each country has typical or average weather.In the Philippines, April and May are the warm summer months, while July and August are the rainy months.

The average weather in a region over a period of time is called climate.

Climate is the weather condition of a place over a long period of time.

Thus weather is very variable and can be described as fair, rainy, sunny, or stormy.

THE EARTH IS DIVIDED INTO THREE ZONES

(1)The zone of tropical climate, (2)The zone of temperate climate,and (3)The zone of polar climate These climate zones are related to the angle

at which the sun’s rays strike the earth Thus the general descriptions of climate

conditions in these zones are as follows: 1.Zone of tropical climate – hot humid

climate 2.Zone of polar climate – very cold climate 3.Zone of temperate climate – mild climate

ELEMENTS OF WEATHER The earth’s surface absorbs heat but also

radiates some of this heat but also radiates some of this heat.

The sun’s energy that is absorbed by the earth is spread throughout the atmosphere in

Three basic ways: Conduction, Convection, and Radiation

Conduction is the direct transfer of heat energy from one substance to another.

Convection is the transfer of heat in a gas or liquid.

Radiation is the transfer of heat energy in the form of waves through a vacuum.

QUIZ

1. _ _ t _ _ r _ _ o _ _ _ t are people who study the weather and use weather data to predict the weather.

2.W_ _ _ _ _ _ is the condition of the atmosphere at any given time and place.

3.M_ _ _ _ _ _ l _ _ _ science that deals with weather and climate conditions.

4. _ e _ _ _ r _ _ meaning high in the air 5.L_ _ _ _meaning knowledge

Write the group of words that will correctly complete each sentence.

FILL IN THE BLANK

m e e o o l g i s

e a t h e r

e t e o r o o g y

m t e o o s

o g o s

6.The average weather in a region over a period of time is called c_ _ _ _ _ _.

7.P_ _ _ _ p _ _ _ _ i _ _ is rain, snow, sleet, hail or any other moisture that fails.

8.C_ _ _ _ _ _ _ _ _ is the direct transfer of heat energy from one substance to another.

9._ _ _ v _ _ _ i _ _ is the transfer of heat in a gas or liquid.

10.R_ _ _ _ _ _ _ _ is the transfer of heat energy in the form of waves through a vacuum.

l i m a t er e c i i t a t o n

o n d u c t i o n

C o n e c t o n

a d i a t i o n

TYPES OF CLOUDS Clouds have different shapes and sizes. Clouds are classified according to shape and

altitude. The main types of clouds are cirrus

clouds, cumulus clouds, stratus clouds, and nimbus clouds.

Cirrus clouds are fair-weather clouds. They appear thin and curly.

Cirrus means ‘feathery’. They consist of ice crystals because they are formed under low temperature at high altitudes.

Cumulus means ‘piled’ or ‘heaped up’. Cumulus clouds look like heads of

cauliflower with flat bottoms. These clouds develop when rising

columns of moist air are cooled to the dewpoint temperature.

Stratus means ‘spread out’ or ‘stretched in layers’.

Unlike cumulus clouds, stratus clouds are only a few hundred meters thick but may extend over thousands of square kilometers.

Nimbus means ‘rainy’. Any cloud that produces precipitation is

called nimbus.

AIR MASSES A cold air mass is turbulent because of

the many convection currents affecting it.

The convection currents are caused by the warming of the air when it comes in contact with the ground.

Warm air masses form very few convection currents but form fog and low clouds close to the ground.

This condition develops because the air close to the ground is cooled to a temperature near its dew point.

AIR MASS BOUNDARIES A cold front forms when a mass of cold air

meets and replaces a mass of warm air. A warm front forms when a mass of warm air

overtakes a cold air mass and moves over it. A cold front travels faster than a warm front. When cold front overtakes a warm front, and

is rushed upward, an occluding front occurs. An occluded front produces less extreme

weather than a cold or a warm front. When a warm air masses meets a cold air

mass and no movement occurs, a stationary front forms.

ENUMERATE THE FOLLOWING:

1-4 types of clouds 5-8 types of fronts 9-10 two air masses Answers: 1.Cumulus clouds 2.Cirrus clouds 3.Stratus clouds 4.Nimbus clouds

5.cold front

6.warm front

7.occluding front

8.stationary front

9.cold air masses

10.warm air masses

STORMS AND TYPHOONS Thunderstorms are heavy rainstorms

with thunder and lightning. These storms can be violent.During a

thunderstorm, areas of positive and negative electrical charges build up in the storm clouds.

Lightning is a sudden discharge or spark of electricity between these cloud areas or between a cloud and the ground.

THE CLIMATE OF THE PHILIPPINES

The climate of the philippines may be categorized into three:

1.From March to May–warm and dry seasons

2.From June to November–rainy seasons

3.From December to February–cool and dry seasons

Tropical cyclones, which affect the Philippines during the months of June to November, may be classified into three categories depending on the wind speed.

1.Tropical depression–has a maximum wind speed of less than 63 kilometers per hour(kph).

2.Tropical storm–has a maximum wind speed of 63 to 118 kph.

3.Typhoon–has a maximum wind speed exceeding 118 kph.

The Philippines Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA)

WEATHER FORECASTING

All over the world, weather stations keep track of the presence of cyclones, anticyclones, and weather fronts.

This information is supplied to meteorologists in local weather stations.

The information received is put together or summarized in a weather map.

Stations with the same air pressure are joined by a line.

Such a line is called an isobar.

CLOUD SEEDING Cloud seeding is a method that is used to

control precipitation. This method uses silver iodide particles

spread in clouds to act as condensation nuclei.

Cloud seeding helps disperse fog in airports and, in dry areas, it induces rainfall and snowball.

It ha also been successful in reducing the power of thunderstorms and hurricanes.

Cloud seeding causes droplets of water to evaporate, or turn into a gas.

QUIZMULTIPLE CHOICE:ON THE LINE BEFORE EACH NUMBER, WRITE THE LETTER THE

CORRESPONDS TO THE CORRECT ANSWER.

____1.Which refers to the general conditions of temperature and precipitation over a large area over a long period of time?

a.atmosphere c.latitude b.climate d.weather ____2.What occurs due to the unequal heating of the air? a.conduction c.radiation currents b.precipitation d.convection currents ____3.What instrument is used to measure air pressure? a.altimeter c.psychomotor b.barometer d.thermometer ____4.What term refer to an area where two different air

masses meet? a.front c.low pressure area b.isobar d.high pressure area

b.

d.

b.

a.

____5.Which of the following people study weather? a.astronomers c.meteorolgists b.geologists d.seismologists ____6.What kind of front occurs when a cold front overtakes a warm

front? a.cold c.stationary b.occluded d.warm ____7.What happens to air above a surface when the surface

absorbs more heat? a.becomes warm c.becomes dense b.becomes cooler d.becomes humid ____8.Which layer in the upper atmosphere absorbs ultraviolet rays? a.hydrogen c.water vapor b.ozone d.carbon dioxide ____9.Which area of high pressure contains cold, dry air? a.anticyclone c.hurricane b.cyclone d.tornado ____10.Which type of cloud is feathery and occurs only at very high

altitudes? a.cirrus c.cumulus b.cumulonimbus d.stratus

c.

b.

a.

b.

a.

a.

SEATWORK/HOMEWORK

ANSWERS: Pages 281 to 283