conditions for life on earth Flashcards
how many planets are in our solar system?
9
what is the distance between the sun and the earth?
149.6 million km
how many galaxies are there in the observable universe?
200 billion
how many plants does the universe contain?
10 to the power of 24
what is one main feature of the earth?
it is the only planet that can sustain life
how far away is the nearest earth-like planet?
4.2 light years away
what is the oder of the planets from the sun?
-sun
-mercury
-venus
-earth
-mars
-jupiter
-saturn
-uranus
-neptune
-pluto
what does newtons law of gravity state?
that one object with a mass is attracted to another
define gravity?
a force that keeps objects in place on earth
what is the value of the force of gravity?
around 9.8 ms-2
what happens as the gravitational force increases?
the mass of an object also increases
how was the mass of the earth calculated?
with newtons law of gravity
what is the formula for newtons law of gravity?
F=GmM/r(squared)
who calculated the constant of proportionality?
Henry Cavendish in 1798
what is the formula of newtons second law of motion?
F=ma
who was acceleration due to the force of gravity on earth determined by?
Galileo
who first calculated the radius of the earth?
the Greek Eratosthenes, around 230 BCE, by comparing shadows
what is the formula to calculate the earths mass?
F=GmM/r(squared)=ma
what qualities does water have?
-hydrogen bonds, giving the water molecule stability
-takes a lot of heat to raise the temperature
-it is a good solvent
-it is ideal for metabolic reactions to take place in
what temperature does water freeze at?
0 degrees Celsius
what temperatures does water expand between?
0 and 4 degrees celsius
what temperatures does an enzyme denature?
above 40 degrees celsius
what is the proper name for the atmosphere?
the spheroidal gaseous envelope surrounding the earth
what happens in the atmosphere?
molecule move about randomly and collide with each other, producing pressure
what is the SI unit for pressure?
pascals, Pa
the pressure decreases as we climb up into the atmosphere until it becomes very low, why is this?
because the heavier molecules of the atmosphere are lower down and there are fewer molecules per unit volume
what is the troposphere?
the lowest level of the earths atmosphere and its height changes according to temperature and contains almost all weather
what is the stratosphere?
the layer above the troposphere and the temperature remains constant until we reach about 20km then it increases
what is the stratopause?
the boundary between the stratosphere and the next layer,. the mesosphere
what is the tropopause?
boundary between the troposphere and the stratosphere, it is where the temperature ceases to fall as height increases
what is the main atmospheric gas?
oxygen, O2
at approximately 40-60 degrees latitude there is a marked change what are these known as?
folds
what is the mesosphere?
the layer above the troposphere and the stratosphere
what is the thermosphere?
the upper limits of the atmosphere
as we reach the upper boundary of the mesosphere and move into the thermosphere, we pass into the what?
ionosphere
what is the ionosphere?
an area which contains ions and they are electrically charged and can absorb UV radiation
what are green house gases?
gases that can absorb infrared radiation that is given off from the surface of the earth
what are the two ways in which green house gases can absorb IR radiation?
1) the chemical bonds that hold the molecule together can vibrate and when the bond absorbs energy from infrared radiation it begins to vibrate
2) is to do with the shape of the molecule and its ability to rotate
what gases are able to absorb IR radiation and vibrate? (examples)
-carbon dioxide
-water vapour
what is solar radiation?
the energy that is received on earth from the sun and crosses the area of space that is between us and the sun, it can be felt on the skin as warmth and is visible to the naked eye as sunlight
solar radiation is dominated by the form of energy that is known as what?
electromagnetic radiation
what is a wavelength?
the distance between the peak of one wave to the next, or trough to trough
what are electromagnetic waves?
a mix of electric and magnetic effects, they can spread out through a volume, whether the volume is a gas, liquid or solid and they can also travel through empty space
what are wavelengths measured in?
micrometres
what is solar luminosity?
the power emitted by the sun
on earth, what is water divided into?
reservoirs
what are reservoirs?
the term given to where any chemical or water is stored in nature
what are reservoirs considered to be?
a renewable resource
the earth has a what around the sun which means that although the earth is attracted to the sun, it does not collide with it?
a motion
what is insolation?
the energy arriving per unit area of the earths surface per second, this is the energy that is used to sustain life on earth and which powers climate
what happens to some of the incoming solar radiation when it reaches the earths surface?
-some is absorbed by gases in the atmosphere
-some is reflected or scattered by constituents in the atmosphere
what is the heat budget for the earth?
the difference between the amount of heat received from the sun, plus the small amount we get from the earth itself
what does temperature variation affect?
the heat budget for earth calculation
what are examples of temperature variation?
-spatial variation
-diurnal variation
-seasonal variation
what does spatial temperature variation depend on?
the latitude of the earth
why is there a positive heat balance in the tropics?
because there is more light being received than at higher latitudes
what does diurnal temperature depend on?
the time of day together with different seasons
what does seasonal variation depend on?
the earths orbit around the sun
when is the South Pole nearer the sun?
in UK wintertime
when is the North Pole nearer the sun?
in UK summertime
what is the winter solstice?
day with the fewest daylight hours
what is the summer solstice?
when the sun appears at its highest elevation
what are the tropic of caner and the Tropic of Capricorn defined as?
the latitude at which the sun is directly overhead at noon at the summer and winter solstices
what is the albedo effect?
the reflection and scattering of the light from a surface, it is the amount of solar radiation that is reflected and is related to colour
what is the colour white, in terms of albedo
has the highest albedo and it reflects around 95% of the light that hits it
what is black/tarmac, in terms of albedo?
has a very low albedo, it absorbs more radiation than it gives out and in hot summers tarmac roads get hot and melt from the absorption of radiation
what is albedo expressed as?
a decimal
what is the earths radiation budget?
if the earth and the earths atmosphere retain more solar energy than it radiates back into space, the earth will heat up
what is the magnetosphere?
the region around a planet dominated by the planet’s magnetic field
what are solar winds?
an array of charged particles and radiation that is emitted by the sun
how and why was the magnetosphere created?
it is created by the natural magnetic field of the earth and its created because the earth has an iron core
what are the two protective functions of the magnetosphere?
-by deflecting solar winds, it protects life on earth from harmful charged particles
-has a function of keeping the atmosphere in place
what is the biosphere?
the part of the earth that is capable of sustaining life
what is the theory of panspermia?
the organic molecules needed to create life are brought in on meteorites crashing into the earth
what are hydrothermal vents?
vents under the sea that connect to the deeper layers of the earth and from which spew boiling water and a chemical soup that could possibly be capable of creating and harbouring life
all life on earth is what and what based?
carbon and water based
water is a solvent and when it freezes it what?
floats rather than sinks
what is the result of life emerging meaning the environment changed?
-the formation of eukaryote cells which happened by the symbiosis of bacteria
-it gave rise to the evolution of multicellular organisms
-the ozone layer - formed and began to shield the earths surface from damaging ultraviolet light
where did oxygen come from?
produced by cyanobacteria photosynthesising using sunlight
what is ozone?
a chemical that is made up of three oxygen atoms, its chemical formula is O3
how can ozone be explained?
as a toxic substance that exists in small volumes at ground level, its largest mixing volume is the stratosphere
what is the defining feature of the ozone molecule?
that it can absorb ultraviolet radiation thus protecting life from its harmful effects
there is a what of ozone over the arctic in a seasonal pattern?
depletion
why does the tropical stratosphere receive the most ultraviolet radiation?
as its the area in which most ozone is created due to it receiving the largest amount of solar ultraviolet radiation
what is the carbon sequestration?
term which describes the process from which carbon dioxide from the atmosphere is captured and stored.
how does carbon sequestration occur?
through biological and chemical processes and the carbon enters what are called ‘sinks’
photosynthesis is a form of what?
biosequestration and can be increased by planting forests
what are phytoplankton?
are self feeding (autotrophs) which use carbon dioxide to manufacture organic products which form part of the aquatic food web
what are phytoplankton food source for?
krill
in peat bogs, carbon is retained in a process of what decomposition?
anaerobic decomposition of organic matter and the bog grows, fixing more carbon than it releases
