Thursday, January 30, 2014
Thursday, January 23, 2014
ATMOSPHERE - EXOSPHERE & INOSPHERE
The EXOSPHERE
Very high up, the Earth's atmosphere becomes very thin. The region where atoms and molecules escape into space is referred to as the exosphere. The exosphere is on top of the thermosphere.
This is a picture which shows the Earth, its atmosphere (the clouds are likely in the troposphere and stratosphere), the limb of the Earth (the dark blue curve/edge which is the mesosphere and thermosphere), and the dark blue to black region of space (where our exosphere extends out to...).
Click on image for full size
Image courtesy of NASA
Image courtesy of NASA
The IONOSPHERE
Scientists call the ionosphere an extension of the thermosphere. So technically, the ionosphere is not another atmospheric layer. The ionosphere represents less than 0.1% of the total mass of the Earth's atmosphere. Even though it is such a small part, it is extremely important!
The upper atmosphere is ionized by solar radiation. That means the Sun's energy is so strong at this level, that it breaks apart molecules. So there ends up being electrons floating around and molecules which have lost or gained electrons. When the Sun is active, more and more ionization happens!
Different regions of the ionosphere make long distance radio communication possible by reflecting the radio waves back to Earth. It is also home to auroras.
Temperatures in the ionosphere just keep getting hotter as you go up!
ATMOSPHERE - THERMOSPHERE #8
The THERMOSPHERE
This is an image of the space shuttle as it is orbiting around the Earth. The space shuttle orbits in the thermosphere of the Earth.
Click on image for full size
Courtesy of NASA
Click on image for full size
Courtesy of NASA
The thermosphere is a layer of Earth's atmosphere.
- The thermosphere is directly above the mesosphere and below the exosphere.
- It extends from about 90 km (56 miles) to between 500 and 1,000 km (311 to 621 miles) above our planet.
Temperatures climb sharply in the lower thermosphere (below 200 to 300 km altitude), then level off and hold fairly steady with increasing altitude above that height. Solar activity strongly influences temperature in the thermosphere. The thermosphere is typically about 200° C (360° F) hotter in the daytime than at night, and roughly 500° C (900° F) hotter when the Sun is very active than at other times. Temperatures in the upper thermosphere can range from about 500° C (932° F) to 2,000° C (3,632° F) or higher.
The boundary between the thermosphere and the exosphere above it is called the thermopause. At the bottom of the thermosphere is the mesopause, the boundary between the thermosphere and the mesosphere below.
Although the thermosphere is considered part of Earth's atmosphere, the air density is so low in this layer that most of the thermosphere is what we normally think of as outer space. In fact, the most common definition says that space begins at an altitude of 100 km (62 miles), slightly above the mesopause at the bottom of the thermosphere. The space shuttle and the International Space Station both orbit Earth within the thermosphere!
Below the thermosphere, gases made of different types of atoms and molecules are thoroughly mixed together by turbulence in the atmosphere. Air in the lower atmosphere is mainly composed of the familiar blend of about 80% nitrogen molecules (N2) and about 20% oxygen molecules (O2). In the thermosphere and above, gas particles collide so infrequently that the gases become somewhat separated based on the types of chemical elements they contain. Energetic ultraviolet and X-ray photons from the Sun also break apart molecules in the thermosphere. In the upper thermosphere, atomic oxygen (O), atomic nitrogen (N), and helium (He) are the main components of air.
Much of the X-ray and UV radiation from the Sun is absorbed in the thermosphere. When the Sun is very active and emitting more high energy radiation, the thermosphere gets hotter and expands or "puffs up". Because of this, the height of the top of the thermosphere (the thermopause) varies. The thermopause is found at an altitude between 500 km and 1,000 km or higher. Since many satellites orbit within the thermosphere, changes in the density of (the very, very thin) air at orbital altitudes brought on by heating and expansion of the thermosphere generates a drag force on satellites. Engineers must take this varying drag into account when calculating orbits, and satellites occasionally need to be boosted higher to offset the effects of the drag force.
High-energy solar photons also tear electrons away from gas particles in the thermosphere, creating electrically-charged ions of atoms and molecules. Earth's ionosphere, composed of several regions of such ionized particles in the atmosphere, overlaps with and shares the same space with the electrically neutral thermosphere.
Like the oceans, Earth's atmosphere has waves and tides within it. These waves and tides help move energy around within the atmosphere, including the thermosphere. Winds and the overall circulation in the thermosphere are largely driven by these tides and waves. Moving ions, dragged along by collisions with the electrically neutral gases, produce powerful electrical currents in some parts of the thermosphere.
Finally, the aurora (the Southern and Northern Lights) primarily occur in the thermosphere. Charged particles (electrons, protons, and other ions) from space collide with atoms and molecules in the thermosphere at high latitudes, exciting them into higher energy states. Those atoms and molecules shed this excess energy by emitting photons of light, which we see as colorful auroral displays.
ATMOSPHERE PRESSURE #5
Pushy Pressure
Pressure is the force of one object pushing on another. In the case of the air around you, it is the force of all the air molecules hitting your body. When you are standing on the ground, the pressure is the weight of all the air above you (all the way to the edge of the atmosphere) pushing down on you. Mind you, it doesn't just push down. All of those molecules are pushing sideways, up, diagonally, and every way imaginable.Think about the desk your computer is on. If the force of the air were just down, it would probably collapse. Because the air also pushes up, the desk is able to stay in one piece and not collapse under the weight of your books. Think about when you go swimming. There is pressure all around you from the water. That pressure is from the water molecules around you and the air above the surface. The deeper you go, the more pressure, and you have to pop your ears.
A Little About Gases
The key to understanding pressure in the atmosphere is to understand how gases work. You can read about gases and how pressure can increase and decrease when forces change (like temperature and volume). We're also adding on the idea ofdensity. Density is the amount of a substance in a specific area. Water has a greater density than ice, which has a greater density than water vapor. When you decrease the volume of a container (and keep the same amount of matter) you will increase the pressure. If you increase the temperature of a container, you will increase the pressure.Water is a special case where the solid is actually less dense than the liquid form. Ice floats at the top of your soda because it is less dense than the surrounding liquid. The solid version of most compounds is more dense than the liquid version. Liquid states are always more dense that the gas state (under normal conditions).
Real World Explanations
So you have a hot day. Chances are the pressure will rise when it gets hotter. The molecules are getting more excited and have nowhere to go. They wind up pushing on everything with a greater force. Let's say you're up in the sky. There is less pressure because there are fewer molecules above you pushing on you.That idea explains why the pressure is lower in Colorado than it is on a beach in California. Colorado has a higher altitude. When do you get the greatest pressure? On a hot day? No. Really cold days actually have a higher atmospheric pressure. Why? As the temperature drops, the molecules of the air around you begin to condense and are less excited. These compressed molecules actually create a greater pressure than the excited and hot ones on a warm day. You will be able to prove this fact if you visit Siberia, Russia. Go figure.
Up Up And Away
Let's talk about the very top of the atmosphere. As you move higher above the ground, the temperature will drop and then begin to rise again. The pressure continually decreases. How? There is a lot more energy hitting the Earth from the Sun as you move closer to the outer edge of the atmosphere. This extra energy causes the molecules to get excited and the temperature goes up. As the temperature increases, there is no pressure pushing on the molecules (like on the surface of the Earth) so they can spread out as much as they want. Only gravity pulls on them. They spread out so much that there is actually less pressure than on a place the same temperature lower in the atmosphere.
ATMOSPHERE - MESOSPHERE #7
The MESOSPHERE
This picture explains about the mesosphere. The mesosphere is a layer of Earth's atmosphere. It starts about 50 km (31 miles) above the ground and goes all the way up to 85 km (53 miles) high. The layer below it is called the stratosphere. The layer above it is thethermosphere. The border between the mesosphere and the thermosphere is called the mesopause. Mostmeteors burn up in the mesosphere. A type of lightning called sprites sometimes appears in the mesosphere above thunderstorms. Strange, high-altitude clouds called noctilucent clouds sometimes form in this layer near the North and South Poles. It is not easy to study the mesosphere directly. Weather balloons can't fly high enough and satellites can't orbit low enough. Scientists use sounding rockets to study the mesosphere. The top of the mesosphere is the coldest part of the atmosphere. It can get down to -90° C (-130° F) there! As you go higher in the mesosphere, the air gets colder.
Click on image for full size
Original artwork by Windows to the Universe staff (Randy Russell).
Click on image for full size
Original artwork by Windows to the Universe staff (Randy Russell).
- The mesosphere is above the stratosphere layer.
- The layer above the mesosphere is called the thermosphere.
- The mesosphere starts at 50 km (31 miles) above Earth's surface and goes up to 85 km (53 miles) high.
As you get higher up in the mesosphere, the temperature gets colder.
- The top of the mesosphere is the coldest part of Earth's atmosphere.
- The temperature there is around -90° C (-130° F)!
The boundaries between layers in the atmosphere have special names.
- The mesopause is the boundary between the mesosphere and the thermosphere above it. The stratopause is the boundary between the mesosphere and the stratosphere below it.
Scientists know less about the mesosphere than about other layers of the atmosphere. The mesosphere is hard to study.
- Weather balloons and jet planes cannot fly high enough to reach the mesosphere.
- The orbits of satellites are above the mesosphere.
- We don't have many ways to get scientific instruments to the mesosphere to take measurements there. We do get some measurements using sounding rockets.
- Sounding rockets make short flights that don't go into orbit. Overall, there's a lot we don't know about the mesosphere because it is hard to measure and study.
- Most meteors from space burn up in this layer.
- A special type of clouds, called "noctilucent clouds", sometimes forms in the mesosphere near the North and South Poles. These clouds are strange because they form much, much higher up than any other type of cloud.
- There are also odd types of lightning in the mesosphere. These types of lightning, called "sprites" and "ELVES", appear dozens of miles above thunderclouds in the troposphere below.
In the mesosphere and below, different kinds of gases are all mixed together in the air.
- Above the mesosphere, the air is so thin That atoms and molecules of gases hardly ever run into each other. The gases get separated some, depending on the kinds ofelements (like nitrogen or oxygen) that are in them.
You know that waves can form in the ocean or other bodies of water. But did you know that there are waves of air in the atmosphere? Some of these waves start in the lower atmosphere, the troposphere and stratosphere, and move upward into the mesosphere. The waves carry energy to the mesosphere. Most of the movement of air in the mesosphere is caused by these waves.
Tuesday, January 21, 2014
ATMOSPHERE - STRATOSPHERE #6
The STRATOSPHERE
The stratosphere is the second layer (going upward) of Earth's atmosphere. It is above the troposphere and below the mesosphere. The ozone layer is within the stratosphere.
Click on image for full size
Original artwork by Windows to the Universe staff (Randy Russell).
Click on image for full size
Original artwork by Windows to the Universe staff (Randy Russell).
The stratosphere is a layer of Earth's atmosphere.
- The stratosphere is the second layer, as one moves upward from Earth's surface, of the atmosphere. The stratosphere is above the troposphere and below the mesosphere.
The top of the stratosphere occurs at 50 km (31 miles) altitude. The boundary between the stratosphere and the mesosphere above is called the stratopause.
- The altitude of the bottom of the stratosphere varies with latitude and with the seasons, occurring between about 8 and 16 km (5 and 10 miles, or 26,000 to 53,000 feet).
- The bottom of the stratosphere is around 16 km (10 miles or 53,000 feet) above Earth's surface near the equator, around 10 km (6 miles) at mid-latitudes, and around 8 km (5 miles) near the poles. It is slightly lower in winter at mid- and high-latitudes, and slightly higher in the summer.
- The boundary between the stratosphere and the troposphere below is called the tropopause.
Ozone, an unusual type of oxygen molecule that is relatively abundant in the stratosphere, heats this layer as it absorbs energy from incoming ultraviolet radiationfrom the Sun. Temperatures rise as one moves upward through the stratosphere. This is exactly the opposite of the behavior in the troposphere in which we live, where temperatures drop with increasing altitude. Because of this temperature stratification, there is little convection and mixing in the stratosphere, so the layers of air there are quite stable.
Commercial jet aircraft fly in the lower stratosphere to avoid the turbulence which is common in the troposphere below.
The stratosphere is very dry; air there contains little water vapor. Because of this, few clouds are found in this layer; almost all clouds occur in the lower, more humid troposphere. Polar stratospheric clouds (PSCs) are the exception. PSCs appear in the lower stratosphere near the poles in winter. They are found at altitudes of 15 to 25 km (9.3 to 15.5 miles) and form only when temperatures at those heights dip below -78° C. They appear to help cause the formation of the infamous holes in the ozone layer by "encouraging" certain chemical reactions that destroy ozone. PSCs are also called nacreous clouds.
Air is roughly a thousand times thinner at the top of the stratosphere than it is at sea level. Because of this, jet aircraft and weather balloons reach their maximum operational altitudes within the stratosphere.
Due to the lack of vertical convection in the stratosphere, materials that get into the stratosphere can stay there for long times. Such is the case for the ozone-destroying chemicals called CFCs (chlorofluorocarbons). Large volcanic eruptions and major meteorite impacts can fling aerosol particles up into the stratosphere where they may linger for months or years, sometimes altering Earth's global climate. Rocket launches inject exhaust gases into the stratosphere, producing uncertain consequences.
Various types of waves and tides in the atmosphere influence the stratosphere. Some of these waves and tides carry energy from the troposphere upward into the stratosphere; others convey energy from the stratosphere up into the mesosphere. The waves and tides influence the flows of air in the stratosphere and can also cause regional heating of this layer of the atmosphere.
A rare type of electrical discharge, somewhat akin to lightning, occurs in the stratosphere. These "blue jets" appear above thunderstorms, and extend from the bottom of the stratosphere up to altitudes of 40 or 50 km (25 to 31 miles).
ATMOSPHERE - TROPOSPHERE #5
The Troposphere
The troposphere is the lowest layer of Earth's atmosphere. We live in the troposphere. Weather happens in this layer. Most clouds are found in the troposphere. The next layer up is the stratosphere.
Click on image for full size
Original artwork by Windows to the Universe staff (Randy Russell).
Click on image for full size
Original artwork by Windows to the Universe staff (Randy Russell).
- The troposphere starts at Earth's surface and goes up to a height of 7 to 20 km (4 to 12 miles, or 23,000 to 65,000 feet) above sea level.
- Most of the mass (about 75-80%) of the atmosphere is in the troposphere.
- Almost all weather occurs within this layer. Air is warmest at the bottom of the troposphere near ground level.
- Higher up it gets colder. Air pressureand the density of the air are also less at high altitudes. The layer above the troposphere is called the stratosphere.
Nearly all of the water vapor and dust particles in the atmosphere are in the troposphere. That is why most clouds are found in this lowest layer, too. The bottom of the troposphere, right next to the surface of Earth, is called the "boundary layer".
In places where Earth's surface is "bumpy" (mountains, forests) winds in the boundary layer are all jumbled up. In smooth places (over water or ice) the winds are smoother. The winds above the boundary layer aren't affected by the surface much.
The troposphere is heated from below. Sunlight warms the ground or ocean, which in turn radiates the heat into the air right above it. This warm air tends to rise. That keeps the air in the troposphere "stirred up". The top of the troposphere is quite cold. The temperature there is around -55° C (-64° F)!
- Air also gets 'thinner' as you go higher up. That's why mountain climbers sometimes need bottled oxygen to breathe.
The boundary between the top of the troposphere and the stratosphere (the layer above it) is called the tropopause. The height of the tropopause depends on latitude, season, and whether it is day or night. Near the equator, the tropopause is about 20 km (12 miles or 65,000 feet) above sea level. In winter near the poles the tropopause is much lower. It is about 7 km (4 miles or 23,000 feet) high.
The jet stream is just below the tropopause. This "river of air" zooms along at 400 km/hr (250 mph)!
ATMOSPHERE #3
| Earth's Atmosphere is: A mixture of gases with some suspended solids and liquids.
Three common solids in atmosphere:
Formation of the Atmosphere: The Earth's atmosphere was formed by planetary degassing, a process in which gases like carbon dioxide, water vapor, sulphur dioxide and nitrogen were released from the interior of the Earth from volcanoes and other processes. | ||||||
| Structure of the Earth's atmosphere: (From the ground out to space.) |
Troposphere- approx. ground to 10 kilometers (approx 7 miles up)
Stratosphere - approximately 10 km - 45 km up (approx 7miles-30miles)
Mesosphere - approximately 45 km -95 km up (30 - 50 miles up)
Thermosphere - approximately 95 km -to 500 km (50 miles and up)
|
 |
ATMOSPHERE LAYERS #4
Structure
The Atmosphere is divided into layers according to major changes in temperature. Gravity pushes the layers of air down on the earth's surface. This push is called air pressure. 99% of the total mass of the atmosphere is below 32 kilometers.
- Tropopause - located at the top of the troposhere. The temperature remains fairly constant here. This layer separates the troposphere from the stratosphere. We find the jet stream here. These are very strong winds that blow eastward.
- Ionosphere - This is the lower part of the thermosphere. It extends from about 80 to 550 km. Gas particles absorb ultraviolet and X-ray radiation from the sun. The particles of gas become electrically charged (ions). Radio waves are bounced off the ions and reflect waves back to earth. This generally helps radio communication. However, solar flares can increase the number of ions and can interfere with the transmission of some radio waves.
- Exosphere - the upper part of the thermosphere. It extends from about 550 km for thousands of kilometers. Air is very thin here. This is the area where satellites orbit the earth.
Magnetosphere - the area around the earth that extends beyond the atmosphere.
The earth's magnetic field operates here. It begins at about 1000 km. It is made up of positively charged protons and negatively charged electrons. This traps the particles that are given off by the sun. They are concentrated into belts or layers called the Van Allen radiation belts. The Van Allen belts trap deadly radiation. When large amounts are given off during a solar flare, the particles collide with each other causing the aurora borealis or the northern lights.
Stratosphere - 12 to 50 km - in the lower part of the stratosphere. The temperature remains fairly constant (-60 degrees Celsius). This layer contains the ozone layer. Ozone acts as a shield for in the earth's surface. It absorbs ultraviolet radiation from the sun. This causes a temperature increase in the upper part of the layer.
Mesophere - 50 to 80 km - in the lower part of the stratosphere. The temperature drops in this layer to about -100 degrees Celsius. This is the coldest region of the atmosphere. This layer protects the earth from meteoroids. They burn up in this area.
Thermosphere - 80 km and up - The air is very thin. Thermosphere means "heat sphere". The temperature is very high in this layer because ultraviolet radiation is turned into heat. Temperatures often reach 2000 degrees Celsius or more. This layer contains:
LAYERS OF EARTH'S ATMOSPHERE - VIDEO
Monday, January 20, 2014
Friday, January 17, 2014
ATMOSPHERE - PRESENT-DAY COMPOSITION #2
Present-Day Composition
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C. Argon - 0.9% - Used in light bulbs.
D. Carbon Dioxide - 0.03% - Plants use it to make oxygen. Acts as a blanket and prevents the escape of heat into outer space. Scientists are afraid that the buring of fossil fuels such as coal and oil are adding more carbon dioxide to the atmosphere.
E. Water Vapor - 0.0 to 4.0% - Essential for life processes. Also prevents heat loss from the earth.
F. Trace gases - gases found only in very small amounts. They include neon, helium, krypton, and xenon.
Thursday, January 16, 2014
ATMOSPHERE - INTRODUCTION #1
History
Earth is believed to have formed about 5 billion years ago. In the first 500 million years a dense atmosphere emerged from the vapor and gases that were expelled during degassing of the planet's interior. These gases may have consisted of:- hydrogen (H2)
- water vapor
- methane (CH4)
- carbon oxides.
The hydrosphere was formed 4 billion years ago from the condensation of water vapor, resulting in oceans of water in which sedimentation occured.
The most important feature of the ancient environment was the absence of free oxygen. Evidence of such an anaerobic reducing atmosphere is hidden in early rock formations that contain many elements, such as iron and uranium, in their reduced states.
Elements in this state are not found in the rocks of mid-Precambrian and younger ages, less than 3 billion years old.
One billion years ago, early aquatic organisms called blue-green algae began using energy from the Sun to split molecules of H2O and CO2 and recombine them into organic compounds and molecular oxygen (O2). This solar energy conversion process is known as photosynthesis. Some of the photosynthetically created oxygen combined with organic carbon to recreate CO2 molecules. The remaining oxygen accumulated in the atmosphere, touching off a massive ecological disaster with respect to early existing anaerobic organisms. As oxygen in the atmosphere increased, CO2 decreased.High in the atmosphere, some oxygen (O2) molecules absorbed energy from the Sun's ultraviolet (UV) rays and split to form single oxygen atoms. These atoms combining with remaining oxygen (O2) to form ozone (O3) molecules, which are very effective at absorbing UV rays. The thin layer of ozone that surrounds Earth acts as a shield, protecting the planet from irradiation by UV light.
The amount of ozone required to shield Earth from biologically lethal UV radiation, wavelengths from 200 to 300 nanometers (nm), is believed to have been in existence 600 million years ago. At this time, the oxygen level was approximately 10% of its present atmospheric concentration. Prior to this period, life was restricted to the ocean. The presence of ozone enabled organisms to develop and live on the land. Ozone played a significant role in the evolution of life on Earth, and allows life as we presently know it to exist. REMEMBER:
Formation of the Atmosphere:
The Earth's atmosphere was formed by planetary degassing, a process in which gases like carbon dioxide, water vapor, sulphur dioxide and nitrogen were released from the interior of the Earth from volcanoes and other processes. Life forms on Earth have modified the composition of the atmosphere since their evolution.
Air Pressure:At sea level, the air pressure is about 14.7 pounds per square inch. As your altitude increases (for example, if you climb a mountain), the air pressure decreases. At an altitude of 10,000 feet, the air pressure is 10 pound per square inch (and there is less oxygen to breathe).
Present-Day Composition
C. Argon - 0.9% - Used in light bulbs. D. Carbon Dioxide - 0.03% - Plants use it to make oxygen. Acts as a blanket and prevents the escape of heat into outer space. Scientists are afraid that the buring of fossil fuels such as coal and oil are adding more carbon dioxide to the atmosphere. E. Water Vapor - 0.0 to 4.0% - Essential for life processes. Also prevents heat loss from the earth. F. Trace gases - gases found only in very small amounts. They include neon, helium, krypton, and xenon. |
Sunday, January 12, 2014
Wednesday, January 8, 2014
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