Geography Year 9 revision

Latitude: The Equator is very hot, so anywhere near the Equator are hotter than places near the Poles. This is due to the curvature of the earth and angle of the sun.

At the Equator the sun is usually overhead. It shines straight down and the heat is concentrated on a small area which gets very hot. Nearer the Poles the sun shines more at an angle. The heat is spread over a larger area so temperatures are lower.

Distance from the sea: The distance an area is from the sea, affects its temperature. In summer places inland are warmer than places near the coast. In winter it is the opposite.

This is because the sea (liquids) takes longer to heat up than the land (solids). Liquids stay warmer for longer, they take longer to cool down.

Prevailing winds: Prevailing winds are the direction that the wind usually comes. In Britain the prevailing winds come from the south-west.

They bring cool weather if they blow over cool surfaces (land in winter, sea in summer), warm weather if they blow over warm surfaces (land in summer, sea in winter), wet weather if they blow over sea, dry weather, over land.

Relief (altitude): Places that are high up in mountains have lower temperatures and more rainfall.

Britain has cool summers and mild winters.

We have cool summers because of Britains latitude (50-60 north) it is a long way from the equator, the cooling affect of the sea and prevailing winds from sea. We have mild winters because the warming affect of the sea and the prevailing winds from warm sea.

Rainfall is due to the prevailing winds picking up moisture from the sea:

Frontal rain - warm air rises over cool air.

Relief rain - when warm air is forced to rise over mountains.

Convectional rain - when warm ground warms air next to it then rises causing thunderstorms.

Other parts of the world with British climate are: North-west USA and west Canada, North-west Europe, Southern Chile and Tasmania and South Island of New Zealand. Because they: lie between 40 and 60 degrees north or south of the Equator, mostly on west coasts of continents, have prevailing winds coming from the west and have mountains inland from the coast.

Ecosystem - community of plants and animals which interact with each other and with their non-living environment.The types of plants an animals that grow or live in an environment depend on: climate, soil, rock type and relief:        

Large ecosystems are called biomes, the vegetation is largely determined by climate factors.

Ecosystems have been altered and destroyed by humans, for example 40% of Brazil's original rainforest has been cleared. In Scandinavia large areas of coniferous forests are dying from air pollution called acid rain.

It is hot and wet all year round, and rainfall is heavy and falls during most afternoons, there are no seasons, the weather is very predictable in equatorial climates.

In the morning it is mild but gets warmer until midday when water vapour forms cumulus clouds in the sky they continue to get bigger ans will turn into grey cumulo-nimbus rainclouds, then there is a terrential storm and at night it becomes calm and cool.

Places that are 5 degrees north or south of the Equator have equatorial climates, there is no prevailing winds and the sun is always high in the sky:

Mt Cotopaxi, Mt Chimborazo, Amazon Basin, Congo Basin, Mt Kenya, Mt Kilimanjaro and Indonesia all have equatorial climates.

Not all places near the equator have an equatorial climate, this is because of altitude. Mountains like: Kilimanjaro, Kenya, Cotopaxi and Chimborazo are very high so it can be cold enough to have snow on the mountains.

Tropical rainforests grow in equatorial climates, one third of the world's trees grow there. There are 1,000 diffrent types of trees: Hardwoods-mahogany, greenheart and rosewood. These have been adapted to fit the climate.

Some of the trees have been studied and we have found out that most of our medicine comes from them. Periwinkle is found to help cure children with leukaemia.

The wildlife in the rainforest have very good adaptations. Some species live in the canopy and others live in the under-canopy or on the forest floor or in swamps and rivers. In many areas of the forest wildlife feel threatened by deforestation.

A typical 10 kilometre square of rainforest might include: 750 species of tree, 400 species of bird, 150 species of butterfly, 1,500 species of flowering plant, 20 types of animal, 100 types of reptile, 60 types of amphibian and countless numbers of fish and insects.

Tallest trees - emergents

Wildlife found in tropical rainforest: Monkey, tree, parrot, butterfly, mosquito, jaguar, spider, orchid, anaconda, piranha, frog and alligator.

In the Mediteranean they have very hot and dry summers and mild and wet winters.

Summers are hot and dry because the sun rises higher than places north, and the prevailing wind blows from the warm land which brings hot weather, also because it doesn't blow across the sea it doesn't pick up any moisture.

Winters are mild and wet because the sun is lower in the sky but high enough to keep it hot. Also the sea only loses its heat slowly in the winter. The prevailing winds blow from the opposite direction in the winter, so it blows across the sea which is why it brings warm and wet weather, the air rises over mountains causing there to be a lot of relief rainfall.

Places with a mediterranean climate:

California, Central Chile, South Africa, Mediterranean Sea, South-west Australia and South-east Australia.

Because: they are on the west coasts of continents, between latitudes 30 and 40 degrees north or south of the Equator. In the summer the prevailing winds come from the east and in the winter they come from the west.

In spring there are lots of brightly coloured flowers as they arrive by air or road.The natural vegetation in the Mediterranean is woodland and scrub. They start growing in the rainy season in autumn, because bulbs and scrubs are dormant in the summer because it is too hot begin to sprout. Seeds of annual plants begin to germinate, they continue to grow slowly through the winter when water is available and temperatures are warm, then they flower in the spring.

Vegetation in the Mediterranean:

Pine, Cypress, Cork oak (woodland), Thorn bush, Lavender, Thyme, Rosemary, sweet-smelling herbs (low scrub)

Adaptations:

• Quick life cycle to fit into short growing season.
• Long roots to reach down to underground water.
• Rosemary can roll its leaves up tightly to reduce moisture loss.
• Trees have small, thin, waxy or leathery leaves ro reduce moisture loss.
• trees have thick bark for protection against the heat.

In the desert they have very hot summers and much cooler winters. It is hot in the day and cold at night.

They get hot summers because: latitude-The sun is overhead, Distance from the sea-Land heats up quickly and is a long way from cooling effect of the sea and Prevailing wind-blows from warm land. They get  much cooler winters because: Latitude-The sun is high in the sky but not overhead, Distance from the sea-and loses heat rapidly and is a long ay from any warming effect of the sea, Prevailing wind-blows from the cool land. The desert doesn't have much cloud so land heats up during the day, at night there are no clouds to keep in the heat so the temperatures can get below freezing.

Desert climates are in places where air is descending, in Britain air rises and cools and condenses to give clouds and rain. In deserts the descending air gets warmer and causes evaporation to give cloudless skies, also because there aren't many rivers not much air can evaporate.Prevailing winds don't bring rain from the land, when rain does fall it comes in heavy convectional storms, rainfall is unreliable

Places that have hot desert climates are found:

• In the centre or on the west coast of continents
• Usually between 10 and 30 degree north or south of the Equator
• Where prevailing winds come from dry land.
• Sonoran, Chihuahuan, Sechura, Atacama, Sahara, Arabian, Thar, Namib, Kalahari, Australian.

There is not a lot of water in the desert. Plants and wildlife are adapted to try and get the most water. They have to adapt to living in drought conditions. These plants have to stay dormant for a long time.  Sometime desert rainstorms bring them back to life, because the plants will take advantage of the extra water.

Saguaro cactus: can soak up a thousand litres of water, can store 8,000 litres of water, people lost in the desert have cut open a cactus for water, arms usually grow only after 75 years, spikes reduce moisture lose and keep animals away, thick, waxy skin reflects sun's heat and reduces moisture loss, Cacti seeds can lie dormant for several years until it rains, they have long shallow roots to soak up as much water as possible.

Prickly pear cactus: have a lot of similarities to saguaro cactus, yellow flowers, fleshy stems store water.

some wildlife are only active at night (nocturnal), some burrow into the sand to aviod heat at daytime.

A camel can store water, The gerenuk antelope never drinks-it gets its water off of what it eats, lizards are cold blooded so they need heat to become active. 

In polar regions they have very cool summers and very cold winters. It never gets as high as 10 degrees. It is the latitude that affects the climate. In summer the sun is always low in the sky and the temperature usually doesn't reach above freezing point.In winter the sun never rises above the horizon and it stays below 0 all day.

The air is so cold in polar regions so it doesn't pick up much moisture, so precipitation falls as snow and when it is windy it is blizard.

Tundra and ice cap: Arctic circle, antarctic circle, Greenland, Northern Alaska and Canada, Northern Russia and Antarctica.

It is too cold and dry to grow any trees in the tundra, so only specialised plants can survive in a very short growing season. In the ice caps nothing can grow.

Tundra: migratory reindeer and caribou. Ice cap: polar bears and walrus in Arctic and penguins and whales in the Antarctic.

Climate change is affecting polar regions and the snow and ice is melting which is a huge threat to polar bears.