Atmosfera

The Atmosphere

The atmosphere is an envelope of gases wrapped around the Earth. Its relation to the size of the Earth is similar to that of the skin of an apple. The gases are transparent (allow light and view to pass through them) and odourless. The gravitational pull of the Earth keeps the atmosphere attached to it, although the atmosphere itself is in constant motion.

StructureExosphere

From 500–1,000 km up to 10,000 km, contain free-moving particles that may migrate into and out of the magnetosphere or the solar wind.

Thermosphere

From 80–85 km to over 640 km, temperature increasing with height. The temperature of this layer can rise to 1,500 °C. The International Space Station orbits in this layer, between 320 and 380 km.

Mesosphere

The mesosphere extendsfrom about 50 km to the range of 80–85 km. Temperature decreases with height, reaching −100 °C in the upper mesosphere. This is also where most meteors burn up when entering the atmosphere.

Stratosphere

The stratosphere extends from the troposphere's 7–17 km range to about 51 km. Temperature increases with height. The stratosphere contains the ozone layer, the part of the Earth's atmospherewhich contains relatively high concentrations of ozone. "Relatively high" means a few parts per million—much higher than the concentrations in the lower atmosphere but still small compared to the main components of the atmosphere. It is mainly located in the lower portion of the stratosphere from approximately 15–35 km above Earth's surface.

Ozone Layer

Though part of the Stratosphere. Ozone(O3) in the Earth's stratosphere is created by ultraviolet light oxygen molecules containing two oxygen atoms (O2), splitting them into individual oxygen atoms (atomic oxygen); the atomic oxygen then combines with unbroken O2 to create O3.

Troposphere

Is the lowest layer, which touches the surface of the Earth. The base of the atmosphere is warmed by conduction from the Earth’s surface sothat temperature falls with increasing height above the ground. Percentages of water vapour and carbon dioxide are higher than in other part of the atmosphere. The Earth’s cloud and weather systems are concentrated there. It contains most of the atmosphere’s water vapour, cloud, dust and pollution.

Radiation Balance

Light radiated from the sun is the source of all energy of the Earth. Sunlightis short-wave radiation. On average, only about a half the light is absorbed by the Earth surface. Solar energy absorbed by the surface is transformed into heat, which is long-wave radiation. Some absorption takes places in the atmosphere mainly by gases (18%) Reflection of light into space occurs from clouds, gases and dust particles in the atmosphere and from light-coloured surfaces (32%) Theremainder (50%) is available for absorption to Earth’s surface.

Insolation is the amount of solar energy reaching the Earth’s surface that is available as heat. Rates of insolation vary greatly from place to place; the main control is latitude: insolation is greatest at the equator and in the tropics, where the sun shines overhead from a high angle in the sky all year. The sun’s light has adirect path through the Earth’s atmosphere and less is lost by reflection. In contrast, near the poles the sun’s rays approach the Earth’s surface at an oblique angle, so that each ray has a larger surface area to heat up. A longer journey through the atmosphere means that more of the light is absorbed and reflected, which leaves less to be used for heating up the surface.

On land, snow coveredregions are the coldest places on Earth, Snow has a high albedo. What it means is that a high proportion of sun’s light is reflected instead of being absorbed.

Atmosphere circulation

To understand circulation, we need to be aware of three processes:

1.If air nest to the ground is heated, it expands, gets lighter and rises. This causes a decrease in the amount of air at the ground and the...