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--Sterwick (talk) 17:23, 13 July 2009 (UTC)
What is weather? I'm sure your mum always complains about
weather in Britain! But weather is more than an excuse to moan.
Weather affects our health, culture and evoloution. I'm sure you've
heard about thunderstorms, rain, sun etc, but how do they form?
This page tells you all you must know about weather.
The atmosphere is anything between 'the ground' and 'space'. The
atmosphere is the driving force of the weather, and is vital for
the well-being of all life on Earth. But why?
The atmosphere is sectioned into different layers. Each layer
does different things.
The first layer. It extends to 6km, slightly higher than
Everest. This layer holds the Oxygen we need to breathe and this is
the place weather forms. Without weather, we would have no rain,
how could we live without rain?
The second layer. Extends from 6-30 miles above us. The
Stratosphere is important because The Ozone layer lies in this
zone. The Ozone layer protects us from the harmfull rays the sun
Not just the layer with a catchy name! This layer extends from
30-50 miles. It doesn't really have any specific importance, but
without it, our atmosphere would be a lot thinner, meaning less
protection from dangers in space.
This is the last layer of the atmosphere. It extends from 50-310
miles and is the first line of protection against hazards such as
meteorites ('space rocks'). There is lots of friction here, which
makes it hot enough to burn up most dangers. Temperatures in some
areas may be 1000 °c, or even hotter! Past the Thermosphere is
engine behind weather
What is the engine behind weather? There are three important
engines: the sun, convection, and pressure.
The sun is the main reason why some places are hotter than
eachother. Death Valley, Nevada, experienced the hottest recorded
temperature on Earth, at a scorching 57°c- that's nearly as hot as
your hot tap. The world's coldest recorded temperature was at
Vostock station, Antartica, which recorded a temperature of -89-
colder than your average day on Mars. Death Valley is near the
equator, and Vostock is in Antartica- so the sun must be a big
contributer to heat. Earth, although tilted, has a sort of bulge,
the equator being at the centre of this 'bulge'. The Artic diameter
is much less than the equator's. So in fact, the equator is closer
to the sun than Earth. Another common factor that changes
temperature is altitude (how high you are)
Warm air is much less dense (the particles are much more spread
out) than cold air. In other words, warm air is lighter than cold
air. Because warm air is light, it rises, and because cold air is
heavy, it falls. The warm air rises to a certain height and becomes
cold again (it gets colder the higher into the atmosphere you go);
it may condense (turn into liquid) and become rain. Once the cold
air warms up by being close to the surface, it starts rising,
completing the cycle. Convection is a great engine of weather.
Air pressure greatly affects what kind of weather we experience.
There are two types of air pressure: high pressure and low
This is the type of weather that usually means stormy weather.
Warm air is much less dense than cold air, so it rises. As it
rises, the air cools, condensing to form clouds. Water vapour
condenses in the clouds to form rain.
Although high pressure usually means calm, settled weather, high
pressure is usually cooler than low pressure. Cold air is much
denser than warm air, so it sinks. You end up with settled, but
cool, weather- shame you can't get the best of both!
There are many types of weather that we experience in our daily
lives: you sunbathe when it is hot and sunny; and you put your coat
on when it rains and becomes cold, we all have a pretty good
general idea of weather- but you may not know how they form. We are
going to look at the effect of features on local weather.
We all experience wind. Wind is basicly the movement of air- but
how are some winds different to others?
The sea takes longer to heat up than land. This makes the air
over the land warmer. The warmer land air rises over the sea, and
the air above gets replaced by the cooler sea air, creating sea
breezes. Land breezes are the reverse, and happen because the sea
also takes longer to cool.
and Mountain Winds
The sun heats up the air over Valley Slopes, making the warm air
rise, and have a lower pressure than the air at the same level over
the valley, creating the breeze. Mountain winds are simply the
reverse of Valley Winds.
There are a number of types of precipation. Although sometimes
we moan about it, it's a very important part of life of about every
life form. The types:
This forms from layered clouds. Clouds, caused by condensation
of air, hold small ice droplets, caused by condensed water vapour.
When the ice droplets fall through the cloud to a layer above 0°c,
the droplets melt into drizzle or rain.
Simply rain, but with smaller water droplets.
In thunderclouds, ice droplets falling may be caught in strong
updrafts, they collide with many other ice droplets, growing larger
and larger. Some hailstones may be bigger than golfballs and may
If it is really cold, the ice droplets may not melt as they fall
through the clouds, so they land as snow. The temperature effects
what the snow is like: the shape and hardness.
Sleet are small drops of snow like drizzle is small drops of
rain. This is when rain falls through cold cloud (below 0°c), sleet
is kind of between rain and snow.
Frost is the cold white sheets on grass, and gives a beautiful
crispy texture. There are two types of frost:
This is the most common type of frost and forms in two ways:
1. Dew freezes on grass and other surfaces
2. Water vapour freezes before turning into Dew.
Less common. This is when liquid water below freezing point
(0°c) in fog touch a surface below freezing point and finally
freezes into ice.
There is something about a Thunderstorm that fascinates; perhaps
the boom of a thundercloud, or maybe the danger of a lightning
A good way of remembering the speed of light and sound is to
remember the famous phrase: 'which came first: the thunder or the
Light travels at an astonishing 186,282 miles per second! So we
see lightning almost as it happens. But sound travels much slower
(but it's still very fast). To estimate how far away lightning is,
count the number of seconds between seeing the lightning and
hearing the thunder. Divide by 5 to discover the distance by miles
(or by 3 for km).
How they are
The stages of a thunderstorm.
1. A Cumulus cloud grows. Updrafts develop, preventing
precipation from falling.
2. Downdrafts develop, precipation forms. Wind, thunder, and
3. Downdrafts cut off updrafts. Cloud begins to collapse.
Precipation stops. Other clouds may form over the shrinking
Fog is formed when the air becomes saturated. Water vapour comes
in contact with the ground, condensing to form fog.
NOTE: Mist is light fog
There are a number of types of fog. These include Advection fog.
This is when warm ocean air is blown accross a colder landmass, the
vapour falls onto the land. (see convection) Dew is the moisture
that can be seen on grass or other surfaces on those cold mornings.
Like fog, it forms within contact with the ground, direct contact
in this case.
Rainbows are present when the sun is out and it is raining at
the same time. The science of a rainbow is quite complicated: put
simply, sunlight rebounds of the raindrops, extracting all the
sunlight's colours, forming the famous bow.
1. What part of the map do the storm warnings seem to be
2. In which direction is the Hurricane moving in?
3. Using the scale, how far does the storm seem to be moving in
4. What does this mean about the speed?
1. The coast/ beach
3. 250 miles
4. Roughly 10mph
Weather, Reader's Digest