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Earth Science

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Greatest Discoveries with Bill Nye  Earth Science

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National Geographic Documentary   Destructive Weather   HD 2016

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Bill Nye  The Science Guy   S05E16   Storms

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Uploaded by Maybelle COLLINS on 2016-04-25.

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Weather Scope: An Investigative Study of Weather and Climate

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Weather Scope: An Investigative Study of Weather and Climate

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Without our atmosphere, there would be no life on earth. Two gases make up the bulk of the earth's atmosphere: nitrogen (78%), and oxygen (21%). Argon, carbon dioxide and various trace gases make up the remainder.

Scientists divided the atmosphere into four layers according to temperature: troposphere, stratosphere, mesosphere, and thermosphere. The temperature drops as we go up through the troposphere, but it rises as we move through the next layer, the stratosphere. The farther away from earth, the thinner the atmosphere gets.

TROPOSPHERE

This is the layer of the atmosphere closest to the Earth's surface, extending up to about 10-15 km above the Earth's surface. It contains 75% of the atmosphere's mass. The troposphere iswider at the equator than at the poles. Temperature and pressure drops as you go higher up the troposphere.

Q: Why is the troposphere wider at the equator than at the poles?

The Tropopause: At the very top of the troposphere is the tropopause where the temperature reaches a (stable) minimum. Some scientists call the tropopause a "thermal layer" or "cold trap" because this is a point where rising water vapour cannot go higher because it changes into ice and is trapped. If there is no cold trap, Earth would loose all its water!

Most of what we call weather occurs in the troposphere. The uneven heating of the regions of the troposphere by the Sun causes convection currents and winds. Warm air from Earth's surface rises and cold air above it rushes in to replace it. When warm air reaches the tropopause, it cannot go higher as the air above it (in the stratosphere) is warmer and lighter ... preventing much air convection beyond the tropopause. The tropopause acts like an invisible barrier and is the reason why most clouds form and weather phenomena occur within the troposphere.

The Greenhouse Effect: Heat from the Sun warms the Earth's surface but most of it is radiated and sent back into space. Water vapour and carbon dioxide in the troposphere trap some of this heat, preventing it from escaping thus keep the Earth warm. This trapping of heat is called the "greenhouse effect".

However, if there is too much carbon dioxide in the troposphere then it will trap too much heat. Scientists are afraid that the increasing amounts of carbon dioxide would raise the Earth's surface temperature, bringing significant changes to worldwide weather patterns ... shifting in climatic zones and the melting of the polar ice caps, which could raise the level of the world's oceans.

Q: Why is the amount of carbon dioxide in the troposphere increasing?

STRATOSPHERE

This layer lies directly above the troposphere and is about 35 km deep. It extends from about 15 to 50 km above the Earth's surface.

The stratosphere is warmer at the top than the bottom. The lower portion has a nearly constant temperature with height but in the upper portion the temperature increases with altitude because of absorption of sunlight by ozone. This temperature increase with altitude is theopposite of the situation in the troposphere.

14 October 2012: Austrian daredevil Felix Baumgartner made an extreme skydive from the edge of space, leaping off a capsule more than 24 miles (39 km) above the Earth ... that's in the stratosphere. At this extreme altitude and low air pressure, a tear or crack in his pressurized suit or helmet would cause instant depressurization and his blood to "boil". The latter is a condition called "ebullism" that could cause gas bubbles to form in bodily fluids; and blood literally boils.

Q: What is the relationship between atmospheric pressure and boiling point of a liquid?
The Ozone Layer: The stratosphere contains a thin layer of ozone molecules (with three oxygen atoms) which forms a protective layer shielding life on Earth from the Suns harmful ultraviolet radiation. But this ozone layer is being depleted, and is getting thinner over Europe, Asia, North American and Antarctica. "Holes" are appearing in the ozone layer.

Q: Why are there "ozone holes" in the stratosphere?

MESOSPHERE

Directly above the stratosphere, extending from 50 to 80 km above the Earth's surface, the mesosphere is a cold layer where the temperature generally decreases with increasing altitude. Here in the mesosphere, the atmosphere is very rarefied nevertheless thick enough to slow down meteors hurtling into the atmosphere, where they burn up, leaving fiery trails in the night sky.

THERMOSPHERE

The thermosphere extends from 80 km above the Earth's surface to outer space. The temperature is hot and may be as high as thousands of degrees as the few molecules that are present in the thermosphere receive extraordinary large amounts of energy from the Sun. However, the thermosphere would actually feel very cold to us because of the probability that these few molecules will hit our skin and transfer enough energy to cause appreciable heat is extremely low.

The thermosphere corresponds to theheterosphere, a zone where there is no uniform distribution of gases. In other words, the gases are not well-mixed; instead they are stratified that is layered, in accordance to their molecular masses. In contrast, the gases in the homosphere (consisting of the troposphere, stratosphere and mesosphere) are uniformly distributed.

Q: Why are the gases in the thermosphere stratified?

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Without our atmosphere, there would be no life on earth. Two gases make up the bulk of the earth's atmosphere: nitrogen (78%), and oxygen (21%). Argon, carbon dioxide and various trace gases make up the remainder. Scientists divided the atmosphere into four layers according to temperature: troposphere, stratosphere, mesosphere, and thermosphere.

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Earth's Atmosphere

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Earth's Atmosphere - Windows to the Universe

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The atmosphere is an important part of what makes Earth livable. Learn about atmosphere layers, weather, climate and more.

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THE EARTH'S ATMOSPHERE

The Earth's atmosphere is a thin layer of gases that surrounds the Earth. It composed of 78% nitrogen, 21% oxygen, 0.9% argon, 0.03% carbon dioxide, and trace amounts of other gases. This thin gaseous layer insulates the Earth from extreme temperatures; it keeps heat inside the atmosphere and it also blocks the Earth from much of the Sun's incoming ultraviolet radiation.

The Earth's atmosphere is about 300 miles (480 km) thick, but most of the atmosphere (about 80%) is within 10 miles (16 km) of the surface of the Earth. There is no exact place where the atmosphere ends; it just gets thinner and thinner, until it merges with outer space.

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).

The Layers of the Atmosphere:
Thermosphere: The thermosphere is a thermal classification of the atmosphere. In the thermosphere, temperature increases with altitude. The thermosphere includes the exosphere and part of the ionosphere.

*Exosphere: The exosphere is the outermost layer of the Earth's atmosphere. The exosphere goes from about 400 miles (640 km) high to about 800 miles (1,280 km). The lower boundary of the exosphere is called the critical level of escape, where atmospheric pressure is very low (the gas atoms are very widely spaced) and the temperature is very low.

*Ionosphere: The ionosphere starts at about 43-50 miles (70-80 km) high and continues for hundreds of miles (about 400 miles = 640 km). It contains many ions and free electrons (plasma). The ions are created when sunlight hits atoms and tears off some electrons. Auroras occur in the ionosphere.

*Mesosphere: The mesosphere is characterized by temperatures that quickly decrease as height increases. The mesosphere extends from between 31 and 50 miles (17 to 80 kilometers) above the earth's surface.

*Stratosphere: The stratosphere is characterized by a slight temperature increase with altitude and the absence of clouds. The stratosphere extends between 11 and 31 miles (17 to 50 kilometers) above the earth's surface. The earth's ozone layer is located in the stratosphere. Ozone, a form of oxygen, is crucial to our survival; this layer absorbs a lot of ultraviolet solar energy. Only the highest clouds (cirrus, cirrostratus, and cirrocumulus) are in the lower stratosphere.

*Tropopause: The tropopause is the boundary zone (or transition layer) between the troposphere and the stratosphere. The tropopause is characterized by little or no change in temperature altitude increases.

*Troposphere: The troposphere is the lowest region in the Earth's (or any planet's) atmosphere. On the Earth, it goes from ground (or water) level up to about 11 miles (17 kilometers) high. The weather and clouds occur in the troposphere. In the troposphere, the temperature generally decreases as altitude increases.

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.

Web Links about the Earth's Atmosphere
Label the layers of the Earth's atmosphere - a printout
The atmosphere from NASA

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Advertisement. EnchantedLearning.com is a user-supported site. As a bonus, site members have access to a banner-ad-free version of the site, with print-friendly pages. Click here to learn more. (Already a member? Click here.) THE EARTH'S ATMOSPHERE The Earth's atmosphere is a thin layer of gases that surrounds the Earth.