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A Day of Weather |
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| Record it!
Blue Skies
Red Sunsets
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| Daily Changes... | As well as the different seasons we experience, the weather also changes on a more short-term basis – from day to day. Sometimes these daily changes can be even more striking than any longer-term variations. | ||
| Global Changes... | Although in England our weather can change dramatically each day and it is often hard to predict these differences, in tropical regions the variations are more regular and easy to follow. Mornings are often fine and sunny, although thunderclouds can build up quickly as moist air being evaporated by the sun forms large cumulus clouds. The afternoon usually involves a brief rainstorm, although the weather will clear after that to give a clear dusk and evening. |
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| Record it..! | Why not make a note of how the weather changes through the day? You will learn more about weather variations in your area and it may even help you to predict when the sun may come out or when it will rain. |
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Blue skies and red sunsets.Although the weather can change on both a seasonal and daily basis, there are some features that are more constant. One of these is the colour of the sky. Thought: when you paint a picture of an outside scene, you usually include a fairly standard colour scheme: green grass, blue sky and yellow sun. But why do you do that? Answer – because the grass is green, the sun is yellow and the sky is blue! But have you ever wondered why the sky is blue? Let me explain: |
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| Blue skies...
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Sunlight is also known as white light. This is because although it contains all the colours in the rainbow, when they are mixed together they appear white. The sky appears blue because of what happens when white sunlight passes through the Earth’s atmosphere. As we have already discovered, the atmosphere contains many particles of dust, water vapour and other objects. When the light hits these particles, it is reflected in all directions – a process called scattering. Each of the different colours is scattered by a different amount, with the blue light being scattered the most. It is therefore this colour that we see most easily and so when we look at a blue sky, we are simply seeing the blue bit of sunlight being reflected off the particles in the atmosphere towards our eyes. Without this scattering in the atmosphere, a clear sky would look black, except near the sun. | ||
| Red sunsets...
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This scattering of light can also be used to explain why the sky appears red at sunset. At this time, the sun’s rays have to pass through a much greater thickness of atmosphere than they do when the sun is high in the sky at midday. As a result, nearly all the blue light is scattered out by the particles in the air. Much more red light than blue lights is therefore reaching your eyes and the sun and sky appear red in colour. Clouds will also appear red or pink at sunset (or just after sunrise) because they are reflecting the red light of the sun. |
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| Have you heard the expression: "Red sky at night, shepherds delight. Red sky in the morning, shepherds warning"? Stay with us and you'll discover more weather phrases and sayings in the weather lore section. You will even be able to add your own! |
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Well done, you have now finished the introductory What is weather?
section. With the background material covered, it's time to move on and have a look
at some of the tools and techniques used to predict the weather in the Weather
Forecasting section. To do this, click on the sunshine icon below.
Alternatively, you can have a look at some of the Activities related to the
What is Weather section (for example making your own barometer), or return to the Weather Features |
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