The Earth's atmosphere is a thin, gaseous layer of ...
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Transcript of The Earth's atmosphere is a thin, gaseous layer of ...
The Earth's atmosphere is a thin, gaseous layer of molecules surrounding the solid surface of the planet. It is held in place by the Earth's gravity.
The Earth's atmosphere is made up of a mixture of different gases. It has a layered, vertical structure, with different gas compositions, temperatures, and pressures characterizing each layer.
The air particles in the atmosphere are constantly circulating in convection currents due to temperature differences caused by uneven heating from the Sun. Earth's atmosphere is always warmest over the equator and coolest over the poles.
Nitrogen and oxygen are the two most abundant gases; they make up about 99% of the atmosphere's total volume
Usually, water vapor is the third most abundant gas in the atmosphere, though the exact amount of water vapor in the atmosphere can vary. This changing amount of water vapor in the atmosphere is one of the biggest causes of all the weather patterns seen on Earth.
Gas Percent of Composition in Atmosphere
Nitrogen 78.08%
Oxygen 20.95%
Water Vapor 0–4%
Argon 0.93%
Carbon Dioxide 0.036%
Neon 0.0018%
Helium 0.0005%
Methane 0.00017%
Hydrogen 0.00005%
Nitrous Oxide 0.00003%
Ozone 0.000004%
The Earth's atmosphere can be divided into five layers. These layers, in order of increasing altitude (distance from Earth's surface)
● Troposphere: The troposphere is the atmospheric layer closest to the Earth's surface. It is the densest layer, and is where clouds and weather are formed and where people live. The troposphere contains most of the gases and dust of the atmosphere.
●Stratosphere: The stratosphere is above the troposphere. The stratosphere is a cold, dry layer of air. The ozone layer is found within the stratosphere.
●Mesosphere: The mesosphere is the third layer above the Earth's surface. The mesosphere is the coldest layer of the Earth's atmosphere.
●Thermosphere: Above the mesosphere lies the thermosphere. In the thermosphere, even though the air is thin, it is very hot because radiation from the Sun energizes the particles there.
●Exosphere: The exosphere is the uppermost layer of the atmosphere. It has no definite boundary because, with increasing altitude, the air simply gets thinner until the atmosphere blends into space.
Layers of the Atmosphere
Air is made up of molecules of gas and particles of dust, liquid water, and ice. These substances have mass, so they are affected by the pull of the Earth's gravity
The weight of the atmosphere pressing down on the Earth's surface and the random movement of the air particles creates air pressure. As altitude above the Earth's surface increases, the air gets thinner and air pressure decreases.
Air pressure also decreases as the amount of water vapor in the air goes up or when air is warm. Warmer air is less dense than colder air and therefore exerts less air pressure.
Air pressure can be measured in millimeters of mercury by using a weather tool called a barometer, or in millibars.
The temperature of Earth's atmosphere is not as straightforward as describing its air pressure.
This is because the difference in composition among Earth's atmospheric layers causes them to react differently to the Sun's radiation.
Air temperature decreases moving upward through the troposphere, increases throughout the stratosphere, decreases greatly throughout the mesosphere, and increases greatly throughout the thermosphere
At any altitude, the temperature of the atmosphere can be affected by Earth's seasons, solar wind activity, and many other variables.
The climate of a particular area is a description of long-term weather patterns, including average temperature and precipitation amounts
The climate of a region is influenced by many factors
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Differences in the solar radiation received at different latitudes of the Earth result
in different climate zones. This is why similar patterns can be seen in the Northern
and Southern Hemispheres as warm air from the equator moves toward the poles.
In the Northern Hemisphere
Begins at the equator and extends to about 23°N latitude
The equator receives a greater input of solar radiation than any other location on Earth. This causes the air at the equator to warm. The warm air rises at the equator and moves toward the North Pole until it reaches the beginning of the temperate region.
Begins at about 23°N latitude and extends to about 67°N latitude. At 23°N, warm air arriving from the equator begins to cool and sink toward the Earth's surface.
The sinking air moves along the Earth's surface toward the Equator or toward the northern end of the temperate region (67°N)
At the northern end of the temperate region, air warms and rises. Some of this warm air travels south, where it sinks at the southern end of the temperate region. Some of the warm air travels toward the North Pole
Begins at about 67°N latitude and extends to the North Pole
Warm air traveling toward the North Pole gradually cools as it nears the pole, where solar radiation is very limited. The air becomes very cold and sinks toward the Earth's surface
The descending cold air then travels along Earth's surface back toward the south. As it moves toward the south, the air is gradually warmed and rises again at the boundary between the polar and temperate regions (at about 67°N)
Evaporation
Precipitation The process of water being released from clouds in the form or rain, hail or snow.
Condensation- The process of water vapor turning into liquid water.
Gravity- The force of attraction between two objects because of their masses
Sun Energy- Energy produced or radiated by the Sun.
Groundwater- Water beneath the surface of the ground.
Water vapor - The gaseous phase of water.
Water droplets- The liquid phase of water.
Crystallization- The process by which solids form.
The water cycle is the path that all water follows as it moves around Earth in different states. Liquid water is found in oceans, rivers, lakes, and underground. Solid water is found as snow or ice. The gaseous form of water is found as water vapor in Earth’s atmosphere.
WHAT IS THE WATER CYCLE?
Earth’s water is continuously being moved on, above, and below the surface of Earth. Water is always changing states between liquid, gas (vapor), and solid (ice). Water moves and cycles between the ocean, atmosphere, and land. Water evaporates from the surface of Earth, rises into the atmosphere, cools and condenses, and falls again to the surface as precipitation.
The Cycling of Water
The water falling on land moves along the surface in rivers and streams and collects in bodies of water such as lakes and oceans. Most water that falls on the land soaks into the ground, where it can spend long periods of time trapped in the spaces between rocks and soil. Groundwater is the source of water for plants to grow, and humans have relied on groundwater as a drinking source for thousands of years.
The solar radiation that comes from the Sun contains energy that drives the water to move through the water cycle. The Sun’s heat causes glaciers and snow to melt into liquid water. It also causes water to evaporate from oceans, lakes, and streams.
The process of water evaporating from the leaves of plants is called transpiration. The Sun’s heat also warms water vapor, causing it to rise up through Earth’s atmosphere, where it condenses back into liquid water and creates clouds. All of these processes are driven by energy from the Sun and continually move water through the water cycle.
Sun Energy
Gravity and Water Collection
Gravity is an attractive force that also helps move water through the water cycle. Water is pulled down from higher elevations by gravity into rivers, streams, and underground.
Gravity also pulls water down from the atmosphere when it rains, snows, or hails. Most of the water that falls to the ground will soak into the ground and collect as underground water. When water reaches the ends of rivers or streams, it will begin to collect in bodies of water such as lakes or oceans.
Water is continually moving underground downward and sideways because of gravity and pressure. Groundwater is a major contributor to flow in many streams and rivers and has a strong influence on river and wetland habitats for plants and animals.
The vast majority of groundwater occupies space between soil and rock particles. The ground acts like a sponge as it soaks up water into these spaces.
At a certain depth below the land surface, larger spaces of collected groundwater can be found called aquifers. Water can also hit areas underground that are denser or have less space for water storage such as nonporous rock. This causes the water to flow in a more horizontal fashion, generally toward streams, oceans, or deeper underground.
Groundwater Flow
Landforms, such as mountains, are important to the weather and climate of an area because of the effect that they
have on rainfall.
For example, when rain clouds blow in from the coast toward mountain ranges, the mountains force the clouds to
move upward in the atmosphere. Since the amount of heat in the atmosphere decreases as the distance from the
Earth increases, the water in the clouds cools as the clouds move upward. The cooled water droplets condense,
and the water is released as rain on the near side of the mountains.
The water cycle describes the continuous movement of water on, above, and below the surface of the
Earth. This movement of water in the cycle can have a great influence on weather patterns.
There is much more water being stored at any given time than is moving through the cycle. Water may be
stored for a short time as water vapor in the atmosphere, for days or weeks in a lake, or for thousands of
years in a polar ice cap. However, most of the Earth's water is stored in the oceans.
Movement of Water During the Water Cycle
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● Condensation is the changing of gas to a liquid (water vapor to water) and is crucial for the formation of clouds. Clouds form in the atmosphere when air containing water vapor rises and cools. Water vapor can be present in the air even when clouds are not visible. Clouds become visible when water particles combine with each other around tiny particles of dust to form water droplets.
During infiltration water fills the porous spaces in the rock and soil that makes up the lithosphere. This is one of the main sources of groundwater.
Infiltration
Surface Runoff
● Evaporation takes place largely from the oceans. It often happens as a result of heat produced by the radiant energy from the Sun–liquid water is heated until it turns to a gas (water vapor) and is released into the atmosphere.
Transpiration
Sublimation is the changing of water from a solid directly to a gas with no intermediate liquid stage. The opposite of sublimation is deposition, when water vapor changes directly to a solid. Snowflakes and frost are examples of deposition.
