Weather
The Atmosphere
The atmosphere is a blanket of gases that surrounds our planet. It is made up of many different gases.
The atmosphere is; - 78 % Nitrogen - 21 % Oxygen - 1 % Other Gases (Carbon dioxide, Ozone, Water Vapour). |
Without the atmosphere, there would be no life on earth. It provides us with; - It provides us with the oxygen we breathe. - Protection from the harmful rays of the sun. - It keeps the earth cooler during the day and warmer during the night |
Heating Our Planet
The sun provides all of the heat for our planet. This solar energy provides us with heat and light.
We would not be able to live on planet earth without the energy we get from the sun. However, not all of the solar energy reaches the surface of the earth. 1. Around 25% of the energy is deflected back into space by dust & clouds in the atmosphere. 2. Another 25% is lost as it travels through the earth's atmosphere. 3. Therefore, only 50% of the solar energy makes it through to the surface of the earth. Click Here, to see what happens the solar energy as it travels towards the earth. |
Ocean Currents
All of the earth's oceans have ocean currents flowing through them.
Ocean currents can be Cold Ocean Currents or Warm Ocean Currents. If a Cold Ocean Current flows by a country it makes the country colder. If a Warm Ocean Current flows by a country it makes the country warmer. In the Northern Hemisphere ocean currents flow in a clockwise direction. In the Southern Hemisphere ocean currents flow in an anticlockwise direction. http://davidburchnavigation.blogspot.ie/2013/01/ocean-currents.html |
The Water Cycle
Most of the water on the earth is in the form of salt water in the oceans or ice in the polar ice caps.
The Water Cycle is a process which continually recycles a proportion of the earth's water. There are 4 stages involved in The Water Cycle. These are; 1. Evaporation - Heat from the sun evaporates water from the sea as water vapour. 2. Condensation - The water vapour cools as it rises and condensation takes place. This creates clouds. 3. Precipitation - Rain, hail, sleet or snow falls from the clouds back to the earth. 4. Run-Off - The rain etc eventually flows back into the sea from rivers and the land. |
Types of Rain
Rain occurs when warm moist air is forced to rise.
As the warm air rises it cools. Condensation takes place because cold air cannot hold as much water vapour as warm air. Clouds form and this leads to rain. There are three different types of rainfall because there are 3 different reasons why warm air is forced to rise. The 3 types of rainfall are; 1. Relief Rainfall occurs when warm air is forced to rise because of a mountain. 2. Frontal Rainfall occurs when warm air is forced to rise because of a Front. 3. Convectional Rainfall occurs when warm air is forced to rise because of evaporation |
The Wind
What is wind? The simple answer is that wind is moving air!
But why does the air move? Well that is all to do with air pressure. Air is pulled towards the earth because of gravity. This means that the air has weight. This weight is called Atmospheric Pressure. Some places have Low Atmospheric Pressure while other places have High Atmospheric Pressure. Low Atmospheric Pressure is caused where warm air rises up into the atmosphere.. High Atmospheric Pressure is caused where cold air presses down on the surface of the earth. Air moves from High Pressure areas to Low Pressure areas. This creates wind. To see a diagram of how wind is created Click Here |
Air MassesAn air mass is a large body of air that has the same temperature, humidity, and air pressure. There are 4 different air masses that influence the weather that we have in Ireland. 1. Polar Air Masses - Come from the North and bring cold weather. 2. Continental Air Masses - Form over land in eastern europe and bring dry weather. 3. Tropical Air Masses - Come from the south and bring warm weather. 4. Maratime Air Masses - Form over the Atlantic Ocean and bring wet weather. Over Ireland, many different air masses meet, and so the weather changes all the time. |
FrontsA Front is the boundary area where 2 different air masses meet.
There are 2 types of Front, a Warm Front and a Cold Front. Warm Fronts - These occur where a warm air mass moves in toward and rises above a cold air mass. Warm fronts are displayed on weather charts as a red line with red semicircles on it. Click Here to see an Animation. Cold Fronts - These occur where a cold air mass moves in towards and replaces a warm air mass. Cold Fronts are displayed on weather charts as a blue line with blue triangles on it.
Click Here to see an Animation. |
Weather Systems
Anticyclones are High Pressure weather systems (HIGH). Unlike depressions,
anticyclones are made up of only one air mass. Dry air descends (moves down) from the atmosphere towards the surface of the earth. As it moves down the air warms up, and can hold more water vapour. Therefore, condensation does not take place and clouds cannot form. They bring gentle breezes, clear skies, sunshine and no rain. Depressions, also known as cyclones (LOW), are low pressure weather systems. They begin over the Atlantic Ocean. They bring cloudy, wet and windy weather to Ireland. They form along the Polar Front, where warm Tropical Air Masses coming up from the south meet cold Polar Air Masses coming down from the north. The two air masses do not mix very well because of their differences in Temperature, Humidity, and Air Pressure. The warmer lighter air from the Tropical Air Mass rises up above the cold Polar Air Mass in a spiral motion. This creates a warm front. As the warm air rises it cools and condensation takes place. Clouds are formed and rain occurs. Behind the warm front, a cold front is formed. The cold air moves in to replace the warmer air, forcing the warm air to rise rapidly. The warm air cools and condensation takes place. Large clouds form and heavy rain occurs. Click Here to see an animation of a Depression. |
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Test Yourself!
People who make the weather forecast are called Meteorologists. They collect information on different elements of the weather using different weather instruments. The following instruments are used by Meteorologists ..see if you can match up the description them up with the right picture! Anemometer - Measures the speed of the wind in kilometres. Wind Vane - Measures the direction of the wind. (North, South, East, etc). Sunshine Recorder - Measures the number of hours of sunshine in a day. Rain Gauge - Measures how much rain there is in a day in millimetres. Thermometer - Measures the temperature in Degrees Celsius. Hygrometers – Measure the humidity (level of moisture) in the air. Barometer - Measures the air pressure in millibars. Click on the 'Project Work' section to find out how to make your own instruments. |
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