4th Q Science 5 Lesson 3 - Weather Disturbances -PDF PDF

Preview

Summary

LESSON 3WEATHER DISTURBANCESLearning Objectives: At the end of this lesson, learners are expected to: 1. recall the previous lesson; 2. describe the classification of tropical cyclones; 3. explain the weather disturbances and their effects on the environment; and 4. give the typhoon warning signals....

Description

Princeton Science School

Science and Health 5

LESSON 3

WEATHER DISTURBANCES Learning Objectives: At the end of this lesson, learners are expected to: 1. recall the previous lesson; 2. describe the classification of tropical cyclones; 3. explain the weather disturbances and their effects on the environment; and 4. give the typhoon warning signals. A weather disturbance is any pulse of energy that moves through the atmosphere. It can be the start of a low-pressure system or a start of a storm. There are different types of weather disturbances, some of which are tropical cyclones (tropical depression, tropical storm, typhoon/hurricane), tornado, intertropical convergence zone, and monsoons (northeast and southeast monsoon).

Type of Weather Disturbances Tropical Cyclone Tropical cyclones form in the following conditions: warm waters of at least 26.5 degrees Celsius, high humidity, low wind shear, rapid cooling with height, and a pre-existing weather disturbance at around five degrees latitude away from the equator (555 km). Cyclones develop over oceans with wind speeds that usually decrease when they hit the land. Cyclones last for a few hours to several days. They cause widespread damage to life and property. A cyclone can sometimes encourage the development of a tornado once it hits land. Tropical cyclones are classified by how fast the wind blows. Circulating winds that travel with the speed of less than 60 kph are depressions. When the speed of the wind is between 60 to 118 kph, we call it a storm. A typhoon is the strongest kind of tropical cyclone. It develops a speed of over 118 kph. Tropical Depression A tropical depression may form when a lowpressure area is accompanied by thunderstorms that produce circular wind flow with central winds around 61 km/h (23 to 39 mph), depending on the scale used in various regions of the earth.

Q1/1

Princeton Science School

Science and Health 5

Tropical Storm A tropical storm has stronger sustained winds of 62 to 117 km/h (17-33 mph). It also has a defined surface circulation and a distinctive shape of a cyclone starting to develop, but without the presence of an "eye". Typhoon/Hurricane For typhoons and hurricanes, wind speeds are more than 120 km/h, accompanied by strong winds, rain, hail, and storm surges. Tropical storms develop in a humid place where there is a warm body of water. It draws its energy from the waters and maintains its strength as long as it is over water. It is accompanied by heavy torrential rains. The two terms typhoon and hurricane are used to name tropical storms. Tropical storms are classified by the region where they are formed. "Hurricane (from huracan, meaning big wind used by Native Americans for storms) originate from the relatively colder Western Atlantic Ocean around October.

TYPHOON

HURRICANES

Typhoon" (from tai fun meaning 'great wind' used by Chinese) have winds that develop in the relatively warmer Pacific Ocean around July to November. That is why typhoons are said to be stronger than hurricanes. Typhoons or hurricanes form with the following conditions: when there is a pre-existing weather disturbance, warm ocean water, low atmospheric pressure, high winds, and sufficient force from the Coriolis effect, which is the westward deflection of circulating air due to the shape and rotation of Earth. Tornado A tornado is a rotating column of air usually produced by a severe thunderstorm. It is a column of air with a relatively small diameter, violently rotating . It develops within a convective cloud, and is in

Q1/2

Princeton Science School

Science and Health 5

contact with the ground (or water). Convective clouds, like cumulus and cumulonimbus clouds, are clouds that formed by the rising warm air and sinking cold air within them. A tornado is formed from the ground up. However, highly saturated air dropping from a thunderstorm give the appearance that a tornado is touching down from the sky. A tornado can move from 30 to 70 mph and may last for a few minutes, with intense, targeted damage to life and property if they occur in a populated area due to flying debris and collapsing structures.

Intertropical Convergence Zone The ITCZ is a region around the equator where trade winds from North and South hemispheres converge. The trade winds from the North hemispheres move south while trade winds from the South hemisphere move west. The area where these trade winds meet forces air up the atmosphere, forming a band of clouds that bring rain and occasional thunderstorms. The Philippines is often affected by the ITCZ. Monsoon A monsoon is a continuous shift in prevailing wind directions. This seasonal change can bring about heavy rainfall and harsh weather. Our country experiences two monsoons: the northeast monsoon or Hanging Amihan and the southwest monsoon or Hanging Habagat.

What happens before, during and after a cyclone? Dark and cloudy skies signal an approaching tropical cyclone. Later, cold winds blow. You will observe that leaves fall off from twigs and branches. Umbrellas are of no use because they are turned inside out. This could be accompanied by heavy rains, lightning and thunder. There is a time when the wind slows down. You would think the cyclone is gone because the sun even shines and everything is peaceful. But no, the calm center or the eye of the typhoon is over your area. This calmness can last for several hours. Then, the winds start to blow hard again .

Q1/3

Princeton Science School

Science and Health 5

A typhoon may last for 15 hours or it could remain in the Philippine Area of Responsibility for one to seven days. There had been some typhoons that left the country but came back. Typhoons can be very dangerous. Strong winds can uproot trees and topple down electric posts. Due to the heavy rains, they bring floods it can also occur and bring about loss of lives, damage to properties and crops. Communication and transportation are cut off. Roads and bridges are not passable. Ship travel and air flights are cancelled. Trade and commerce are hampered because goods and products from the provinces cannot be transported to commercial areas After a strong typhoon, people are left homeless. Houses are totally wrecked by the wind. Hectares of rice lands and vegetable plantations are destroyed. During strong typhoons, classes are suspended and office and factory workers are sent home. Public Storm Warning Signals (PSWS) Public Storm Warning Signals (PSWS) are raised when there is real and immediate threat from a tropical cyclone to any part of the country. PAGASA (Philippine Atmospheric Geophysical and Astronomical Services Administration) is the government agency that monitors the weather. It collects information from the different weather stations all over the country. Its important job is to make weather forecasts and warn the people of typhoons entering the Philippine Area of Responsibility (PAR). PAGASA gives us these four typhoon warning signals: Typhoon Warning Signal No. 1 A weather disturbance is in the area. Winds with speed of less than 60 kph may be expected in the next 36 hours. People are advised to listen to weather reports more often. Typhoon Warning Signal No. 2 Winds of 60 to 100 kph may be expected within the next 24 hours. People are advised to reinforce houses made of light materials. Classes in the elementary and high school levels are suspended. Typhoon Warning Signal No.3 The weather condition may be dangerous. Winds greater than 100 kph up to 185 kph are expected within 12 to 18 hours. Electric power and communication services may be cut off. People are advised to stay indoors. Classes in all levels and in some offices are suspended. Typhoon Warning Signal No. 4 A very strong wind of more than 185 kph may be expected in less than 12 hours. The typhoon maybe very dangerous and destructive. People should stay indoors. It is too late to evacuate.

ENRICHMENT ACTIVITY A. Directions: Answer the following. 1. Your family planned to hold a beach party for your birthday. List down different sources of weather forecasts you can use to check if it can push through. 2. Which one are most updated and reliable? Why?

References:

Q1/4

Princeton Science School

Science and Health 5

Investigating Life’s Wonders Science 5 ‘’Science Series for Elementary’’. pp. 290-294. Milagros S. Ignacio, Irene P. Santiago, Maria Niña C. Torralba and Annalynn V. Orcine-Authors/Editor Science and You 5 / Science, Health and Environment Series. pp.197-204. Diana L. Ferre, Thelma R. Mingoa, Ph.D., Alicia L. Padua and Crescencia C. Joaquin, Ph.D.-Authors Lilia M. Rabago, Ph.D – Author/Editor

Q1/5...