fluid environment and behaviour Flashcards
what was the earths atmosphere when it was first formed?
it was initially surrounded by gas molecules gravitationally attracted to its surface from the gas molecules and dust rings surrounding the newly born sun.
what did the primary atmosphere consist of?
This primary atmosphere consisted mostly of hydrogen, helium and traces of other gases.
what happened to the atmosphere due to the heat?
Heat from the sun caused light atoms in it to move around so rapidly, that they eventually escaped the attraction of the earth’s gravity. The primary atmosphere leaked out into space, blown away from the solar winds.
what did the secondary atmosphere consist of?
volcanic activity caused this, as it releases a new set of gases. The elements in these gases had been bonded to minerals inside the earth. Water vapor, CO2, SO2, N2, and NH3. the secondary atmosphere consisted of these gases, plus some gases brought to earth by some comets.
what happened when the earth cooled sufficiently?
When the earth cooled sufficiently for water to condense, around 3.8 Ga, rain extracted most of the water from the atmosphere.
when the earth cooled and the water condensed, what happened to the earth?
this water made the lakes, filled the oceans, streams, or sank underground to become groundwater. The concentration of CO2 in the atmosphere began to decrease when this occurred. This is due to the CO2 dissolved in oceans and them combines with calcium to form solid carbonate. Co2 also reacts with rocks exposed on the surface of continents to produce solid chemical weathering products.
what did UV radiation cause in the secondary atmosphere?
UV radiation from the sun split apart molecules of NH3 into nitrogen and hydrogen atoms. The H escaped to space, but the N formed N2, and due to it being unreactive with rocks, it has stayed in the atmosphere for a long time. Due to the new accumulation of N2 molecules, and the loss of water vapour and CO2, the proportion of N gradually increased.
when did photosynthetic organisms appear?
3.8 Ga
what happened to the oxygen when life started?
It took the appearance of life on earth to introduce oxygen to the atmosphere, as O2 is produced due to photosynthesis. The first photosynthetic organisms, cyanobacteria, appeared on earth at around 3.8 Ga, and began to add oxygen to the atmosphere.
what does dry air consist of?
Dry air consists of 78% nitrogen, 21% oxygen. Remaining 1 % consists of other gases such as CO2, CH4 which are greenhouse gases that regulate the earths atmosphere.
what do greenhouse gases allow?
Greenhouse gases allow solar radiation from the sun t o pass through, but trap infrared radiation rising form the earths surface. Trace gases also contain O3, ozone, which protects the surface from UV radiation. In addition to these gases, the air contains traces of aerosols. These tiny particles of liquid or solid material, are so small that they remain suspended in river water.
what are aerosols?
Aerosols include tiny droplets of water and acid and microscopic particles of sea salt, volcanic ash, clay, soot and pollen.
how has human activity increased pollutants? (3 areas)
Human activity has added a substantial amount of pollutants to the air, due to fossil fuel burning and industrial operations. Pollutants include sulfate and nitrate molecules, which react with water to make a weak acid that falls as acid rain. Where acid rain falls, lakes and rivers become acidic and toxic to fish and life in the water sources. The burning of fossil fuels has increased the amount of CO2 in the atmosphere, this contributes to global warming. Atmospheric scientists have discovered that some pollutants react with UV light from the sun to release Cl atoms which react with the ozone, and break it down. These reactions appear to happen mainly in high clouds above polar regions during certain times of the year.
how do elevations determine the weight of air?
In the earths gravity field, the weight of air at higher elevations presses down on and compresses air at lower elevations.
what is air pressure and what does it do?
Air pressure- the push the air can exert on its surroundings. And air density, therefore increases towards the surface of the earth. Beacuse of the density of a gas reflects the number of gas molecules in a given volume, a gulp of air on top of mount Everest where the air pressure is about one third taht of sea level, contains about a third of O2 molecules than that of sea level.
what is 1 atm?
1 atm is approx the pressure exterted by the atmosphere at sea level.
how many molecules lie below an elevation of 5.6 km and why?
Because of the decrease in air density with elevation, 50 % of the amtopsheres molecules lie below an elevation of 5.6 km.
where is the boundary of gas density?
Even though the outer edge of the atmosphere, a vague boundary where the gas density becomes the same as interplanetary space, lies as far as 10,000 km away from the earths surface, most of the atmospheres molecules lie within a shell only of 0.5% as wide as the solid earth.
what are the molecules doing in the atmosphere?
The molecules that constitute the atmosphere are not standing still but are constantly moving. The total kinetic energy. Resulting from the movement of molecules in a gas as its not the same- a gas’s temperature is a measure of the average kinetic energy of its molecules.
how many molecules are in a volume of gas?
A volume of gas with a small number of rapidly moving molecules has a higher temperature, but may contain less heat than a volume with a large number of slowly moving molecules.
