♥LAYERS OF THE ATMOSPHERE♥

ATMOSPHERE
ATMOSPHER	What is weather ? The four main ingredients which cause weather are the Sun, the atmosphere, water vapour and the wind. These all work together, spreading the Sun's heat around the world and making clouds, rain and snow. Weather is an endless cycle of events. The changes over a longer period of time, then it is called climate.
ATMOSPHERIC COMPOUNDS
ATMOSPHERIC ENERGY
OVERHEATED EQUATOR DRIVES WEATHER
What is the atmosphere? Earth is surrounded by an atmosphere, continually in motion, about 800 km deep which protects it from harmful solar radiation and supports all living things. The atmosphere is divided into five layers - exosphere, thermosphere, mesosphere, stratosphere, troposphere.
TROPOSPHERE The troposphere is the atmospheric layer closest to the planet and contains the largest percentage of the mass of the total atmosphere. It is characterized by the density of its air and an average vertical temperature change of 6 degrees Celsius (C) per kilometer. Temperature and water vapor content in the troposphere decrease rapidly with altitude. Water vapor plays a major role in regulating air temperature because it absorbs solar energy and thermal radiation from the planet's surface. The troposphere contains 99 % of the water vapor in the atmosphere. Water vapor concentrations vary with latitudinal position. They are greatest above the tropics, where they may be as high as 3%, and decrease toward the polar regions.
Stratosphere The stratosphere is the second major strata of the atmosphere. It resides between 10 and 50 km above the planet's surface. The air temperature in the stratosphere remains relatively constant up to an altitude of 25 km. Then it increases gradually to 200-220 degrees Kelvin (K) at the lower boundary of the stratopause (~50 km). Ozone plays the major role in regulating the thermal regime of the stratosphere.
The ozone layer is located at an altitude between 20-30 km. Approximately 90 % of the ozone in the atmosphere resides in the stratosphere. Ozone absorbs the bulk of solar ultraviolet radiation in wavelengths from 290-320 nm. These wavelengths are harmful to life because they can be absorbed by the nucleic acid in cells. Large amounts of solar ultraviolet radiation would result in a host of biological effects, such as a dramatic increase in cancers.
Mesosphere The mesosphere, a layer extending from approximately 50 km to 80 km, is characterized by decreasing temperatures, which reach 190-180 K at an altitude of 80 km. Thermosphere The thermosphere is located above the mesosphere and is separated from it by the mesopause transition layer. The temperature in the thermosphere generally increases with altitude up to 1000-1500 K.
Exosphere The exosphere is the outermost region of the Earth's atmosphere. The exosphere begins at approximately 500 km and extends outward until it transitions with interplanetary space (at roughly 10,000 km).
ATMOSPHERIC COMPOUNDS It is made of air which is a mixture of oxygen (21%), nitrogen (78%), carbon dioxide (0.037%) and other gases such as hydrogen, helium, argon, neon, krypton, xenon and ozone. It also contains water vapour. These gases are densest at the Earth’s surface and get less dense with increasing height. Around 90% of the atmosphere by weight lies in the lowest 15 km (9 miles) above the surface and it is only a very thin skin of air that keeps all life on Earth alive. What gives sky its colour ? On a bright, sunny day, you may wonder why the sky appears blue rather than other colors. The secret is the size of air molecules. They are the perfect size for scattering blue light out of the incoming sunlight. The sun appears yellow because the other colors of the incoming sunlight usually pass through the air uninhibited. If you were to look at the sun in outer space, it would appear white. Other particles in the atmosphere such as dust and cloud droplets can team up to create beautiful sunrises and sunsets.
Air molecules in the atmosphere scatter blue light from sunlight During the broad daylight hours, the scattered blue light makes the sky appear blue Sunlight runs out of blue light during long trek through air, making sky appear red, orange or yellow
ATMOSPHERIC ENERGY
The Sun is the ultimate source of heat energy of the earth. All the Earth's heat and light comes from the Sun. The heat and light reaches the Earth from the Sun in one minute is more than the amount of the whole world can produce in a year. The Sun keeps the temperature of most of the Earth' surface at -51 to 49 degrees Celsius. Most living things can only survive at 0 to 49 degrees Celsius. If the amount of sunlight reaching the Earth was cut by one tenth, the oceans would turn to ice and life on Earth would die. The Sun is the key to the world's weather. Its rays filter through the atmosphere and warm the Earth's surface which, in turn, heats the air above. This makes the air move because warm air rises. As the rising warm air moves farther away from the land, it cools and sinks. Air moves all over the world, causing winds which carry weather changes. Also, the Equator is hot because the Sun shines directly overhead. The Poles are cold because the rays hit the Earth at lower angles.
OVERHEATED EQUATOR DRIVES WEATHER The sun is the driving force behind weather. As solar energy reaches the Earth, equatorial regions heat up more than the poles. Warm air and water at the equator travel pole-ward while cold air and water at the poles travel equator-ward in an attempt to equalize this temperature contrast. It is the atmosphere's continual struggle for temperature balance that brings us our changing weather.
Solar energy heats equator more than the poles Warm air, water flows to colder poles while cold air, water flows to warmer equator
Earth’s tilt creates seasons. The reason for the changes in Earth's seasons is the Earth's tilt, not its distance from the sun. In the Northern Hemisphere summer, the land north of the equator is tilted towards the sun, allowing more of the sun’s energy to heat the Northern Hemisphere. Conversely, during the Northern Hemisphere winter, the land north of the equator is tilted away from the sun, which lowers the amount of the sun’s energy warming the Northern Hemisphere. The Earth is actually closer to the sun during the Northern Hemisphere winter, but since the hemisphere is tilted away from the sun, it still feels like winter. Why is the Earth warmer when we're farther from the Sun? It's because there's more land in the northern hemisphere and more water in the south. During July the land-crowded northern half of our planet is tilted toward the Sun. Land warms faster than the water.