SCIENCE02L31: Weather, Part 1: What Causes Weather Changes

OBJECTIVES ❖ Define weather ❖ Name and describe the different kinds of weather ❖ Enumerate the elements that cause weather changes ❖ Describe and identify the different kinds of clouds ❖ Cite activities that can be done in a particular weather ❖ Identify clothes and other things used for a particular weather ❖ Enumerate ways on how to keep safe during any kind of weather LESSON PREREQUISITES None LESSON PROPER The condition of Earth’s atmosphere at a given time and place is called weather. The atmosphere is the layer of gases that surround Earth. Among these gases are those that make up the air that you breathe. The weather changes from day to day. On some days, the weather is warm or sunny. On other days, it is rainy. You can tell the kinds of weather you will be having by looking at the clouds and feeling the wind. Kinds of Weather Weather can be described as sunny, cloudy, windy, rainy, or stormy. During sunny weather, the sun shines brightly, and the air feels warm. White, featherlike clouds appear high in the sky. You can also describe this kind of weather as fine. During cloudy weather, the sky is filled with many cottonlike clouds, but there is no rain. A cloudy weather is a fair weather. On a windy weather, the wind blows hard. Leaves from trees may be blown away by the wind. Tall plants and branches of trees sway as the wind blows. On a rainy weather, dark clouds in the sky bring rains that may last for a day or longer. On a stormy weather, the sky is covered with thick dark clouds, which bring the heavy rains. Winds are also strong. Sometimes, thunder and lightning occur. Heavy rains may cause flooding in some areas. Elements That Affect Weather Conditions Changes in weather are caused by changes in the atmosphere. These changes are caused by air temperature, wind, and clouds. Air Temperature Air temperature as a weather element is the measure of hotness or coldness of air in the atmosphere. You use a thermometer to know the temperature of the air during a certain time. A thermometer is an instrument with a long tube that contains a liquid like mercury or alcohol. The liquid rise or fall inside the tube, which indicates the hotness or coldness of the air. Printed on the sides of the tube are numbers. The numbers on the left use degrees Celsius (°C). The numbers on the right use degrees Fahrenheit (°F). The sun powers up the weather as its rays warm the air in the atmosphere. Air in areas that are directly hit by the sun’s rays gets warmer that the air in the areas not directly hit by the sun’s rays. The difference in air temperature causes air movement. Wind Moving air is what we call wind. Warm air, which is lighter, rises. Cool air, which is heavier, sinks. The wind also affects weather conditions. During daytime, the land area absorbs more heat faster than the water area or the sea. As the air from the land becomes warmer and rises, the cooler air from the sea takes the place of the warmer air. The cool air coming from the sea during the daytime is called sea breeze. During nighttime, the land cools down faster than the water. As this happens, the cool air from the land takes the place of the warm air over the sea. The cool air blowing in from the land to the sea in the nighttime is called land breeze. Clouds and Rain Clouds and the rain that they bring also affect weather conditions. When warm air rises, it cools. When the air cools, the water vapor in the air turns into tiny water droplets or clouds. The cloud droplets may join up and form bigger and heavier droplets. When the air can no longer hold the water vapor in it, the water vapor falls to the ground as rain, or in some parts of the world, as snow. Types of Clouds 1. Cumulus clouds are fluffy, white clouds that look like cotton. They indicate fair weather. 2. Cirrus clouds are the highest clouds. They look like feathers. They indicate good weather. 3. Stratus clouds are low, gray clouds. They bring light rain or drizzle. 4. Nimbus clouds are thick, dark clouds that usually indicate stormy weather. The Weather Chart Knowing the kind of weather helps us plan for our activities. We can look at a weather chart to know what kind of weather to expect for the day, and even for the next days. A weather chart shows the weather condition of a place at a particular time of the day. A weather chart also shows what kind of weather to expect for the next days. There are people whose work is to observe conditions of the atmosphere to predict the weather as accurately as possible. They are called weather forecasters. They warn people of possible heavy rains or storms through a weather chart. The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) is the agency responsible for assessing and forecasting weather, flood, and other conditions essential to the safety and welfare of the people.