Monday, February 25, 2013
Sunday, February 24, 2013
Friday, February 22, 2013
At the beginning of autumn, temperatures are mild.
Towards the end of autumn, temperatures get colder.
It often rains.
At the beginning of autumn, days and nights are the same length.
Then, the nights get longer.
On many trees, the leaves turn yellow and brown.
At the end of autumn, the leaves fall from these trees.
Summer is the hottest season.
It does not rain very much.
At the beginning of summer, the days are longer, and the nights are shorter.
At the end of summer, days and nights are the same length.
Many plants dry up because there is very little rain.
Spring is the mildest season.
Temperatures are warm, and it often rains.
At the beginning of spring, days and nights are the same length.
At the end of spring, the days are longer, and the nights are shorter.
Flowers and grass start to grow.
Leaves start to grow on trees.
Tuesday, February 19, 2013
Climate is the typical weather conditions in one area.
Different parts of the Earth have different climates.
- Mountain climate. Temperatures are low. It snows a lot in winter.
- Coastal climate. Temperatures are mild all year round.
- Continental climate. In areas a long way from the coast, temperatures are very low in winter and high in summer. It doesn’t rain much.
Wind is the movement of air. There are different types of wind:
- A breeze is a very light wind.
- A gale is a very strong wind.
- A hurricane is an extremely strong wind with rain. Hurricanes are dangerous and can destroy buildings and trees.
Precipitation is water that falls to Earth from the clouds.
Precipitation can fall as:
- Rain is water that falls to Earth as a liquid.
- Snow is water that falls to Earth as frozen snowflakes.
- Hail is water that falls to Earth as small pieces of ice.
Monday, February 18, 2013
The atmosphere is the layer of gases that surrounds the Earth.
The atmosphere has two main parts:
• The lower part contains the air we breathe. Rain and wind are produced in this part.
• The upper part contains very little oxygen, so we could not breathe in this part.
People and animals need air to breathe.
Plants need air during photosynthesis.
Air is also needed for:
- Hearing. Sound travels through air. We cannot hear sound without air.
- Flying. Birds, butterflies and aeroplanes cannot fly without air.
- Burning. Fire needs oxygen from the air in order to burn.
Air is the mixture of gases that surrounds the Earth.
The main gases in air are:
Friday, February 15, 2013
Air moves and occupies space.
Air is a mixture of gases.
One of these gases is oxygen.
Weather can be hot or cold, sunny or cloudy, dry or rainy.
Air can be calm or windy.
Weather changes with each season: spring, summer, autumn, winter.
Sunday, February 10, 2013
Friday, February 8, 2013
When rain falls on the land, it forms streams.
Streams flow into rivers.
Rivers flow into seas and oceans.
When snow melts, it flows into the streams and rivers and finally reaches the sea.
Sometimes, rainwater and melted snow sink deep into the ground to form aquifers.
Water from wells and springs comes from aquifers.
|Photo from: "Banco de recursos del ITE"|
As clouds move across the sky, the tiny water droplets in the clouds join together to form larger drops.
These large drops of water fall to the land as rain.
When rain freezes, it falls to the land as snow or hail.
Water is continually moving around the Earth.
This causes the water cycle.
The water cycle begins when water from the oceans, lakes and rivers heats up and evaporates to form water vapour.
Water vapour passes into the cold atmosphere.
The cold temperature makes the water vapour cool down and condense.
Condensed water in the atmosphere turns into tiny water droplets and forms clouds.
Clouds move across the sky with the wind.
|Photo from: "Banco de recursos del ITE"|
Wednesday, February 6, 2013
In winter water freezes and becomes ice and snow in cold weather.
In spring and summer ice and snow melt and turn into liquid water again.
The coldest areas on Earth are the North Pole and the South Pole.
These areas are covered with giant blocks of ice.
Sometimes, large pieces of ice break off and float in the ocean.
These are called icebergs.
|Iceberg. By Rghrous|
|Photo from Literativa|
Groundwater is fresh water found beneath the surface of the Earth.
When it rains, water goes through the soil and collects in empty spaces between rocks and sand.
Here it forms large deposits called aquifers.
People build wells to collect this water.
|Well. Photo by Roger May|
On the surface of the continents, there is water in rivers, streams and lakes.
This is called fresh water because it contains very little salt.
People, animals and plants drink fresh water.
This is called drinking water.
Drinking water must be clean.
|Stream. Photo by Mann jess|
Most water on Earth is in the seas and the oceans.
Water from the seas is called salt water because it contains a lot of salt.
In order to use salt water, the salt must be eliminated at desalination plants.
This process is expensive and uses a lot of energy.
|Desalination Plant. By roplant.org|
Monday, February 4, 2013
All living things need water to live.
People need to drink water.
We also have many other uses for water, for example in factories and on farms.
Plants take in water through their roots.
Animals need to drink water.
|Water for cleaning. ICStarzz|
|Water for drinking. Joost Nelissen|
|Water for cooking. Gourmet|
|Water for having a shower. Balaji.B|
|Water for watering plants. Samuel_belknap|
|Water for washing clothes. KrashbandyKay...|
|Animals need water to drink. InvincibleTucan|
|Animals need water to live. Hans|
|Water for washing hands. Ms Tina|
A change of state occurs when water cools or heats up.
- Melting occurs when ice is heated and it turns into water.
- Freezing occurs when water cools and turns into ice. Water freezes at 0 ºC. This is its freezing point.
- Evaporation occurs when water heats up and turns into water vapour.
- Condensation occurs when water vapour cools and turns into liquid water.
|Photos: Blender Ice Cubes by ChojinDSL; Isolated Water Crown by MyTudut; Steam by westy559|
People, animals and plants need water to live.
THE DIFFERENT STATES OF WATER
Water can exist in three different states: as a liquid, a solid, and a gas.
- Water is a liquid.
- Ice is a solid.
- Water vapour is a gas.
|Picture from English is incredible|