L.3: The Atmopshere

Which of these is a trace gas in the atmosphere?

Argon

As altitude increases in the atmosphere, air density decreases _____________ the decrease in air pressure.

in a very similar way as

The main reason nighttime radio broadcasts can be sent over long distances is because:

the low D-level region of the ionosphere is weaker at night.

Trace gases do not have an effect on climate.

False

Hot, humid air is heavier than hot, dry air....true or false

False. Humid air contains more water vapor molecules. The molecular weight of H2O is 18 mol-1, which is less than the molecular weight of air (28.96 mol-1).

Carbon cycle

Illustrated the movement of a gas in and out of the atmosphere. -Sources: decay of plants and animals, burning of fossil fuels, among others. -All vegetation contain carbon and release it when they decay or burn -Fossil fuels are also formed from the remains of plants and animals that lived (and died) millions of years ago through complex geologic processes--therefore, carbon is also released when these fossil fuels are burned for energy -Sinks: vegetation, oceans CO2 levels have risen 39% since 1800s

Other Atmospheric divisions

This portion of the atmosphere is referred to as the homosphere. Above the homosphere, where the atmospheric composition is less uniform, is called the heterosphere. The ozonosphere is the zone in the upper atmosphere (11 to 60 kilometers) where atmospheric ozone is concentrated.

Which of the following weather variables always decreases as we climb upward in the atmosphere?

pressure

Atmosphere

100 kilometers above the Earth as the "top of the atmosphere." The top of the atmosphere is the bottom line of earth's energy budget, the Grand Central Station of radiation. It is the place where solar energy (mostly visible light) enters the Earth system and where both reflected light and invisible, thermal radiation from the Sun-warmed Earth exit. The balance between incoming and outgoing energy at the top of the atmosphere determines the earth's average temperature. The ability of greenhouses gases to change the balance by reducing how much thermal energy exits is what global warming is all about." _______________________________________

The peak of Mount McKinley, or Denali, is over 20,000 feet above sea level in Alaska. Anchorage is 160 miles away, yet on a sunny day you can easily see the mountain. If you were brave (or zany) enough to climb to the peak, what percentage of ALL MOLECULES in the atmosphere would you be above?

50%

Exosphere

500 km above Earth's surface, atoms and molecules can escape into outer space. -Known as the upper limit of the atmosphere -Within the exosphere, atoms follow ballistic trajectories and rarely undergo collisions because the density of atoms in this region is so low. -10,000km

Hydrologic Cycle

For a gas in the atmopshere to change, there must be a source or sources that supply gas to the atmopshere and/or sinks that remove a gas from the atmosphere. -The route by which a gas enters or leaves the atmosphere is referred to as a CYCLE. -The supply of a particular gas to the atmosphere is a SOURCE, and a SINK is the mechanism that removes a gas from the atmosphere. Hydrologic Cycle - Cycles water which is 70% of Earth's surface. The major sink of water is precipitation, and the source is the oceans. A cycle of precipitation, runoff/infiltration, evaporation or transpiration, condensation..

Approximately 99.9% of the atmosphere is located in the 30 miles closest to the surface.

TRUE

Mesosphere

Temp decreases with height -Little heat input from the sun in this atmosphere layer and it is far from the earth (a source of re-radiated heat). - COLDEST LAYER at an average of approx. -86º -Top of the mesosphere is approx. 85 km and it is called the mesopause -Ozone and water vapor are negligible -Enriched with lighter gases

Troposphere

Temp decreases with height. -Contains the active and changing weather -78% of atmosphere's total mass and all of Earth's living things -6º per kilometer temperature change -Temp and water vapor decrease rapidly with altitude -Contains 99% of WV in atmosphere -Region of mixing *A narrow zone called the tropopause separates the troposphere from the next highest layer called the stratosphere. Air temperature within the tropopause remains constant with increasing altitude.

Thermosphere

Temp increases rapidly with height, due to absorption of solar rays by oxygen molecules. -Warmest layer -Air density is extremely low, thermometers wont even work because too few particles would strike it enough to heat it -100-200 km, the major components are still nitrogen and oxygen -Oxygen molecules are widely scattered in this portion of the atmosphere, which is probably best known because ionization within this layer often results in the colored glowing lights, known as Aurora Borealis/Australis (80 - 160 km)

Stratosphere

Temp increases with height, which is caused by trace gases (ozone) absorbing solar radiation. ^^Temp inversion -10-50 km above surface -Temp constant until 25km -WV content is very low -Temp increases with ozone concentration

Standing at the top of a tall mountain, a breath of air would contain a lot fewer molecules than a breath of air taken at sea level. But the proportion of oxygen in the two breaths of air, relative to the other constituents, would remain the same.

True

Which of these features does NOT characterize weather?

Vorticity

Weather

Weather is what is happening in the atmosphere (its condition) at any given location and moment. The following features characterize weather: -Air temp -Air pressure -Humidity -Clouds -Precip -Visibility -Wind

If you were to take a breath of pure oxygen, from a tank, you would be getting about ______________ the amount of oxygen you would get by taking a normal breath of our atmosphere.

five times

There is a lot of mixing and overturning of air in which of the following atmospheric layers?

troposphere

The gas that shows the most variation from place to place and time to time in the lower atmosphere is ___________.

water vapor (H2O)

Ionosphere

Additionally, we can also consider the portion of the atmosphere that is electrically charged, that is, where a fair amount of ions and free electrons are located. This region is called the ionosphere, and it begins approximately 60 kilometers above the earth's surface. The ionosphere is important to AM radio communications, as radio waves travel different lengths according to the electrical characteristics of this zone. Located within the thermosphere, the ionosphere is made of electrically charged gas particles (ionized). Divided in three layers; F-Layer, E-Layer and D-Layer Has the important quality of bouncing radio signals transmitted from the Earth. Its existence is the only reason people can be reached via radio.

Air density

Force of gravity compresses air molecules together near the earth. Air density is the number of air molecules in a certain space (volume). The force of gravity is greater closer to the earth's surface, and therefore, more air molecules are held more closely together. Air density greater at the surface. Temperature, pressure, and water vapor content all affect the density of air. For reference, atmospheric density at mean sea level at a temperature of 15 degrees Celsius is 1.225 kg m-3, while the density for liquid water is about 1025 kg m-3. In other words, water is over 800 times denser than the atmosphere. *** Notice on the figure below that air density decreases rapidly at first, then at a slower rate as you move into higher levels of the atmosphere. Also note that air pressure and air density are closely related--as air pressures increases, air density increases as well.

Outgassing

Millions of years pass and the outpouring of gases into the atmosphere continues, a process called outgassing. Outgassing provided a supply of water vapor, which formed into clouds. Eventually, water was released from these clouds and became rivers, lakes, and oceans on the earth's surface. At this same time, carbon dioxide dissolved into the ocean and became locked up in sedimentary rocks such as limestone. With the removal of large amounts of water vapor and carbon dioxide from the atmosphere, it eventually became rich with nitrogen. As you know, nitrogen is the predominant gas in our atmosphere today. Oxygen likely began to increase in concentration as rays from the Sun separated water vapor (H20) into hydrogen and oxygen. The hydrogen, which is a light gas, probably escaped into space, while the oxygen remained. Afterwards, there might have been just enough oxygen for the evolution of primitive plants approximately 2-3 billion years ago. The growth of plants further increased oxygen in the atmosphere through the process of photosynthesis. In this process, plants (when sunlight is present) combine carbon dioxide and water to create oxygen, which is released into the air. Eventually the oxygen in the atmosphere reached today's levels.

IMPORTANT

Moist air is also less dense than dry air, due to the weight of a water molecule compared to oxygen and nitrogen, the main components of our atmosphere. More water vapor, means less room for oxygen and nitrogen and, thus, lighter air. WATER VAPOR AND CO2 CREATED EARTHS ATMOSPHERE Water vapor, which varies over time and space, is a greenhouse gas and an important component of our atmosphere. Most of the water on our planet is believed to have come from the earth's hot interior through outgassing. Carbon dioxide is an important greenhouse gas in Earth's atmosphere; its concentration has been increasing since the early 1800s. Nitrogen and oxygen are both permanent gases, which make up most of Earth's atmosphere. However, the 1% of trace gases are important to weather and climate. The most significant trace gases are water vapor, carbon dioxide, and ozone.

Air pressure

The amount of force over a given surface area is called air pressure. -Near the surface, the number of air molecules and, therefore, weight of the air is much greater than it is higher in the atmosphere. - Air pressure, then, is increases near the surface and decreases as you move into the upper levels of the atmosphere. * For reference, air pressure near sea level is about 1013 millibars, on Mt. Everest it is closer to 337 millibars. -Pressure decreases exponentially with height (meaning decreases rapidly at first and then at a slower rate as you move higher in the atmosphere) by approximately 10 millibars per 100 meters. *** Additionally, approximately 99.9% of the atmosphere in with 30 miles of altitude.

Climate pg 15

The average of all weather elements over a long period of time is climate.

Variable gases

Those that vary spatially and temporally. -Water vapor, carbon dioxide, methane, nitrous oxide, ozone

Permanent gases

Those whose fractional concentrations remain nearly unchanged in the atmosphere, from space to space, time to time. The two most abundant gases are both permanent gases: nitrogen (78%) and oxygen (21%) - together accounting for 99% of Earth's atmosphere. -Other permanent gases include argon, hydrogen, and helium.