martes, 18 de diciembre de 2012
lunes, 17 de diciembre de 2012
sábado, 15 de diciembre de 2012
Population density
Population density is the relation between the number of inhabitants of a place and the surface that this place occupies.
In general it is considered that an area is little populated when it has a density of 10 inha./km2. And it is a very populated
area, if the density exceeds 80 inha./km2.
In general it is considered that an area is little populated when it has a density of 10 inha./km2. And it is a very populated
area, if the density exceeds 80 inha./km2.
Model of population cycle
The model of demographic
transition progresses in four stages:
-Old or preindustrial demographic regime: it is
characterized by high mortality and natality rates. Sometines Mortality rate is
higher than natality rate, therefore there is a negative natural increase.
-First transition: keep the high natality rate, but
mortality decrease, because of andvances in sanitation and health care.
-Second transition: the natality rate begins to
decline, but mortality is still down, so there is balance.
-Modern demographic regime: mortality and natality are
very low and sometimes natality rate falls so much that there is a negative
natural increase.
The model of demographic
transition progresses in four stages:
Map of countries of the European Union
Actually there are 27 countries in the European Union. Some states today have their origin in the very recent changes that have occurred since 1989, after the fall of communism in Eastern Europe.
miércoles, 12 de diciembre de 2012
World water cycle
The water is continually moving.We call to these different stages water cycle.
1.Evaporación: The Sun heat the Earth surface and the water evaporates. The Sun also evaporates water from river, lakes, oceans. Plants form more water vapour with traanspiration.
2.Condesación: The vapour cools and then it rises up, this process forms the clouds.
3.Precipitación: whuen water from the clouds falls as snow, rain or hail.That happen because the small droplets of water that form the clouds become heavy.
4.A part of the water goes to rivers and lakes seas or oceans. And the process repeat itself.
5. The other part of the water is absorbed by the land and form aquifers.
World climatological map
On Earth are three defferetent climatic zones according to latitude: a hot zone, two temperate zones and two cold regions. With these have got these features types:
- Warm climates are found in the intertropical zone.
- Tropical climate.
- Desert climate.
- Temperated climates are between the tropics and polar circles.
- Maritime or oceanic climate.
- Continental climate.
- Cold climates occur in the polar regions and high mountain areas.
- Climate of high mountains.
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