The atmosphere is a layer of air that surrounds the Earth. Clouds form in the atmosphere. The atmosphere regulates electrical and magnetic forces. It absorbs energy
from the sun and protects us from solar radiation and the cold of space.
Air is all around us. Air is a mixture of gases; mostly nitrogen and oxygen. It also contains water vapour.
The air is always moving. Wind is air in motion. During the day the sun warms up the Earth and the air in the atmosphere. When air gets warmer, it rises because it is lighter than cold air. Cold air enters the space abandonded by the warm air.
The Five Layers of the Atmosphere
The troposphere provides the weather. In this layer the Earth absorbs the Sun's energy and heats the air. When warm air rises it forms clouds. Warm air also causes rain and wind.
The Stratosphere is the layer where jet planes fly. The ozone layer is also in this layer. The ozone absorbs harmful ultraviolet rays from the Sun.
The mesosphere layer is the coldest layer of the atmosphere. Sometimes we can see meteors in this layer.
The thermosphere is where beautiful aururas occur. It is also the layer where astronauts orbit the Earth.
The exosphere is the upper layer of the atmosphere. In this layer matter escapes into space.
The Elements of Weather
When we measure temperature, we measure the heat or cold in an object or substance. When the temperature is high, we feel warm. When it is low, we feel cold.
Wind is air in motion. Wind is caused by differences in air temperature in the atmosphere.
Humidity is the amount of water vapour in the air. When humidity is low, the air feels dry. When humidity is high, the air feels wet.
Rain is a type of weather precipitation. The heat fro the Sun evaporates water from oceans, lakes and rivers. Water vapour rises and expands to form clouds. When the water in clouds cools, it rains.
Measuring the Weather
We measure temperature with a thermometer.
A rain gauge measures how much rain falls. It is an open ended tube with a marked scale.
Anemometers measure wind speed and direction. An anemometer has 3 or 4 cups mounted on the ends of spokes. The spokes spin on an axle.
To measure the amount of water vapour in the air we use a hygrometer. This measures how much humidity there is in the air.
A thunderstorm is an electric storm. Thunder is the sound of exploding air. Lightning is a bright flash of electricity.
Snowstorms are storms with lots and lots of snow.
Floods happen after very heavy rain, when a lot of snow melts or when rivers rise. If a flood happens very quickly, it is called a flash flood.
Droughts occur when it doesn't rain or rains very little for a long time.