Atmosphere, Weather and Biogeochemical Cycles

Flashcards about Earth's atmosphere, weather, and biogeochemical cycles based on lecture notes.

What is the atmosphere made of?

Nitrogen (78.0%), Oxygen (20.9%), Argon (0.9 %), Trace gases: CO2(.02%), Ne, He, CH4, H2, Kr

What converts the nitrogen we breathe into a usable form?

Nitrogen-fixing bacteria in the soil

How did scientists think the composition of the atmosphere was like in its first billion years?

Intense volcanic activity producing mostly CO2. As the planet cooled, water vapor condensed and formed the oceans, allowing CO2 to dissolve.

What happened approximately 2 billion years after the Earth's formation?

Algae and green plants evolved and began photosynthesizing, decreasing atmospheric CO2 and increasing O2.

What is a barometer?

A tool that measures air pressure.

How is the atmosphere divided?

The atmosphere is divided into imaginary layers based on temperature trends as you move further from the Earth’s surface.

What are the characteristics of the troposphere?

Closest to the earth, contains 75% of the atmosphere's mass, weather occurs here, thickest at the equator, thinnest at the poles.

What are the characteristics of the stratosphere?

It contains the ozone layer, which protects Earth’s surface from dangerous UV radiation.

How does Ozone affect temperature in the stratosphere?

The ozone layer absorbs ultraviolet radiation from the sun, causing the temperature to increase throughout the stratosphere.

What are the characteristics of the mesosphere?

The middle layer where most meteors burn up.

What are the characteristics of the thermosphere?

Air is very thin, the International Space Station and Aurora Borealis are located within this layer, and solar radiation first hits this layer.

What are the characteristics of the exosphere?

The outer edge of our atmosphere that extends for thousands of miles and gradually fades into space; satellites orbit here.

Why do we have different seasons?

The tilt of Earth’s axis.

What season is it when a hemisphere is tilted towards or away from the sun?

Towards the sun: summer; away from the sun: winter; neither towards nor away: spring or autumn.

How does the heating of the earth create wind?

The unequal heating of the earth.

What are the three main circulation patterns on Earth?

Hadley cells, Ferrel cells, and Polar cells

How do areas of rising and falling air lead to creation of rainforests and deserts?

Rising air creates an area of low pressure, producing rainfall; descending air creates an area of high pressure, preventing rainfall.

How does the Coriolis effect impact wind patterns?

Varying speeds of points on earth cause air to fall behind or push ahead as it moves towards or away from the equator, creating circular air currents.

What is the function of nitrogen and phosphorus in our bodies?

Nitrogen is needed for amino acids and proteins, DNA, and RNA. Phosphorus is needed for DNA, RNA, ATP, and the phospholipid bilayer.

Why is gaseous nitrogen in the atmosphere difficult to break down?

It has a triple bond that makes it hard to break apart and use.

How is nitrogen gas "fixed" into other forms?

Protists, fungi, and bacteria convert N2 into ammonia (NH3) using nitrogenase; ammonia becomes ammonium (NH4+) when mixed with water; nitrifying bacteria turn ammonia into nitrites (NO2-) and nitrates (NO3-).

What is denitrification?

It is the process by which nitrate is converted back into nitrogen and oxygen.

What are the parts of the nitrogen cycle?

Lightning, nitrogen-fixing bacteria, assimilation, nitrification, denitrification

What is unique about the phosphorus cycle?

Phosphorus is found in rocks, so this cycle does not involve the atmosphere. When rocks are weathered through rain and erosion, dissolved phosphorus can enter bodies of water or soil.

What are the main parts of the phosphorus cycle?

Weathering, plants, animals, fertilizer runoff & erosion, marine animals and plants and dissolved phosphates

How have humans affected the nitrogen and phosphorus cycles?

They have introduced synthetic fertilizers for agriculture, overloading ecosystems with too much nitrogen and phosphorus.

How does carbon cycle through Earth and the atmosphere?

Carbon can cycle very quickly from the atmosphere to plants, then to animals, soils and back to the atmosphere and slowly as it travels though ocean sediments, volcanoes, and the atmosphere.

How have humans altered the carbon cycle?

Humans have accelerated the addition of carbon dioxide to the atmosphere through the burning of fossil fuels which causes the ocean to be more acidic, threatening ocean life.