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Thursday, February 10, 2011

Climate and Weather

Hey, today I will be covering the definition of Climate and Weather.

First off, I will be covering the definition of climate. Climate covers the topics of temperature, humidity, atmospheric pressure, wind, rainfall and other various factors. Climate is usually contrasted against weather. The latter is the present condition of these same elements and their variations over shorter time periods. The climate of a location is affected by its latitude, terrain, and altitude, as well as nearby water bodies and their currents. As of now, we have already studied the various climate types of tropical (Singapore), temperate (U.S.A), arid (Siberia), polar (Antarctica), mountainous (Himalayas), mediterranean (Greece).

A tropical climate is a climate of the tropics. In the Köppen climate classification it is a non-arid climate in which all twelve months have mean temperatures above 18 °C (64 °F).  In the tropics, rainfall is relatively high and allows for the growth of tropical rainforests.

Due to the effect of sun angle on climate most areas within the tropics are hot year-round, with diurnal variations in temperature exceeding seasonal variations. Seasonal variations in tropical climate are dominated by changes in precipitation, which are largely influenced by the tropical rain belt or Intertropical Convergence Zone (ITCZ), a portion of the Hadley cell. Areas of ascending air have heavy rainfall; areas of descending air are dry. The ITCZ somewhat follows the solar equator throughout the year, but with geographical variations, and in some areas (India) is heavily influenced by local large-scale monsoon circulations.

We all know the fact that a temperate climate usually has 4 seasons, them being summer, spring, autumn and winter. Temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold. But in continental areas, such as Asia and central North America the variations between summer and winter can be extreme. Most of the world's population live in temperate climates due to the high amounts of land mass within the areas of the polar circles and tropics.

A region of space is said to be arid when there is an absense of water sources and water bodies nearby. This lack of water bodies hinder the growth of natural vegetation and to some extent hinder the growth of animal life due to the lack of vegetation as a source of food. Environments subject to arid climates are usually called xeric or desertic. This lack of water in arid environments can defer based on where the water is present. A hot desert with alot of water vapor in the air does not allow much plant and animal life as the water is not readily assessible to living things.

The Earth's polar regions are the areas of the globe surrounding the poles known as the frigid zones. The North pole and South poles being the centers, are dominated by polar icecaps, resting respectively on the Arctic Ocean and continent of Antarctica.

Polar region receive less intensive solar radiation as the sun's energy arrives at an oblique angle, spreading over a larger area, and also travels a longer distance through the Earth's atmosphere in which it may be absorbed, scattered or reflected, which is the same thing that causes winters to be colder than the rest of the year in temperate areas.

The axial tilt of the Earth has a major effect on climate of the polar regions. Since the polar regions are the farthest from the equator, they receive the least amount of sunlight and are therefore frigid compared to the tropics. The large amount of ice and snow also reflects a large part of what little sunlight the Polar regions receive, contributing to the cold and to a certain extent, can be connected to  the topic of global warming. Polar regions are characterized by the polar climate, extremely cold temperatures, heavy glaciation wherever there is sufficient precipitation to form permanent ice, and extreme variations in daylight hours, with twenty-four hours of daylight in summer, and complete darkness at mid-winter.

The mountainous climate is also known as the alpine climate. In the Köppen climate classification the alpine climate is part of "Group E," along with the polar climate. Certain highland climates can also fit under hemiboreal climate or Semi-arid climate groups of climate classification. This climate gets colder the higher the elevation due to the lapse rate of air.

Typically, a Mediterranean climate is found in most of the lands in the Mediterranean Basin as part of subtropical climate. Worldwide, this is where the largest area of this climate type is found. However, beyond the Mediterranean area, this climatic type prevails in much of California, in parts of Western and South Australia, in southwestern South Africa, in isolated sections of Central Asia and in parts of central Chile.

The climate is characterized by warm to hot, dry summers and mild to cool, wet winters. Mediterranean climate zones are associated with the five large subtropical high pressure cells of the oceans, the Azores High, South Atlantic High, North Pacific High, South Pacific High, and Indian Ocean High. These high pressure cells shift poleward in the summer and equator-ward in the winter, playing a major role in the formation of the world's tropical deserts and the zones of Mediterranean climate polar ward of the deserts. For example, the Azores High is associated with the Sahara Desert and the Mediterranean Basin's climate. The South Atlantic High is similarly associated with the Namib Desert and the Mediterranean climate of the western part of South Africa. The North Pacific High is related to the Sonoran Desert and California's climate, while the South Pacific High is related to the Atacama Desert and central Chile's climate, and the Indian Ocean High is related to the deserts of western Australia (Great Sandy Desert, Great Victoria Desert, and Gibson Desert) and the Mediterranean climate of southwest and south-central Australia.

And with that, I conclude on my blogpost on the Climate and basic description of weather.



  1. Hello everyone :)

    I would like to comment on Matthew's post, specifically on the part of mountainous climate.

    Better known as alpine climate, one distinct characteristic is that it becomes significantly colder at higher elevations. This is due to the simple fact that air tends to get colder as it rises, since it expands.

    The dry adiabatic lapse rate is 10 °C per km of elevation or altitude, meaning that moving up 100 meters on a mountain is roughly equivalent to moving 80 kilometers towards the pole. However, this relationship is only approximate, since local factors such as proximity to oceans can drastically modify the climate. I predict that the presence of oceans would make the nearby surroundings colder, and also create more wind. This is further supported by the fact that the main form of precipitation is often snow, often accompanied by stronger winds. As a result, the presence of oceans may increase the dry adiabatic lapse rate in that region.

    Do correct me if I'm wrong, and feel free to add on to my points. Thank you! :D


  2. Thanks Matthew for your post!

    In addition to your write-up for Temperate Climate, I would like to mention that the Temperate climate can be further classified into maritime and continental. Maritime climate is strongly influenced by the oceans, which maintains fairly steady temperatures across the seasons. E.g. Western Europe, in particular, the UK, and western North America at latitudes between 40-60 degrees North

    Continentality, on the other hand, increases inland, with warmer summers and colder winters as the effect of land on heat receipt and loss increases. E.g. North America, where the north-south aligned Rocky Mountains act as a climate barrier to the mild maritime air blowing from the West.