2 - climate changes Flashcards
what’s the climate?
- Climate is the aspect of the physical environment that most influences ecosystems, constituting the prevailing conditioning for organisms
what determines the climate?
composition of the atmosphere
What is the relationship between a body’s temperature and the wavelength of radiation it emits?
- The wavelength of radiation emitted by a body is a function of its temperature
- For example, the sun, with an average surface temperature of 5800°C, emits shortwave radiations
- while the earth, with an average surface temperature of 15°C, reradiates energy at relatively long wavelengths.
net-radiation
what does the intercepted solar radiation vary with?
- latitude
- season
variation in solar radiation causes large variations in ___ ?
temperature
- with latitude
- seasonally and daily
seasonal and daily variations in temperature caused by variations in solar radiation
- More homogenous in tropical region
- Differences in season, day and night
- differences in the intensity of solar radiation reaching the earth’s surface generate temperature differences which
- together with the effects of the earth’s rotation, originate winds and ocean currents by convection
- means: i.e. the process of heat transfer from one location to the next by the flow of fluids from a high temperature location to a low temperature location
- These, in turn, influence the distribution of precipitation, and play a crucial role in transferring heat from the equator to high latitudes
relationship between air temperature and density
- air expands when heated
- contracts when cooled
- hot air is less dense than the surrounding matter because there is more space between the molecules
- air floats upward
concept:
- Differences in height
- Fluid warm: expands
- Fluid cold: becomes more dense
what happens as air moves upward?
- temperature decreases
- due to adiabatic cooling
vertical temperature gradients due to ___?
- Greater air density near the surface (collision between molecules generates heat)
- “Warming effect” of the earth’s surface
- Adiabatic cooling (caused by gas
expansion as pressure decreases)
what is generated by changes in air temperature combined with earth’s rotation?
- the circulation of air masses
- Coriolis effect: Deflection in the pattern of air flow
- Clockwise movement in N hemisphere, counterclockwise in S. Hemisphere.
- Less dense air in warm areas –> moves up and tends to cool down –> starts moving and gets colder and colder –> ends at pole –> circulation
- 3 cells north and 3 cells: trade wind belts
- More rain where air goes up –> areas of globe naturally more and others naturally less rainy
- greater density near surface creates heat
- As we move up, pressure decrease, air expands, tends to cool down earth temp.
what does solar energy, wind and earth’s rotation generate?
- the oceans currents
- precipitation patterns
precipitation patterns
- Rain, where air cools down when moving up
Relationships between air moisture and temperature
- Certain air temp. has a certain saturation vapor pressure (roter punkt)
- Sat. vaporation pressure = max water you can have in a mass of air as vapor
- Now I am at hellblau: same amount of vapor in it –> warm air moves up, it cools down, then temperature drops, I go go orange point, amount of vapor water stays the same,
- Rain above red line
- No rain below red line
- Causes many temperature changes among different areas (climate change)
what do the arrows show?
three cells and trade wind belts
latitudinal patterns of precipitation follow ___ ?
- the circulation cells
- image: Global pattern of the three cells of trade winds
global pattern of precipitation
what are regional and local patterns of precipitation influenced by?
- topography
do irregular variations in climate also occur at a regional scale?
- yes
- e.g. El Niño Southern Oscillation (ENSO) is a periodic shift of the ocean-atmosphere system in the tropical Pacific
- it impacts weather around the world
- happens every 3-7 years (5 years on average)
- typically lasts nine months to 2 years
- associated with floods, droughts and other global disturbances
ENSO
what do “Microclimates” define?
- the local, small scale conditions in which organisms live
- includes
1. topography (aspect=direction a slope face) 2. light
3. temperature
4. air conditions
5. wind movement
6. moisture etc
what’s the IPCC?
- the Intergovernmental Panel on Climate Change (IPCC)
- the leading international body for the assessment of climate change
- to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts
observed changes in the climate
temperature increase
- human influence has warmed the climate at a rate that is unprecedented (beispiellos) in at least the last 2000 years
- the likely range of total human-caused global surface temperature increase from 1850–1900 to 2010–2019 is 0.8°C to 1.3°C
- with a best estimate of 1.07°C
- Some areas of planet (north) warm more than others
- Areas where climate change is more impacting than in other regions
has the averaged precipitation over land globally decreased? increased? stayed the same?
- has likely increased since 1950
- with a faster rate of increase since the 1980s (medium confidence)
- CNR Data
- tropicalization of rainfall regimes in Italy: on average total rainfall has only slightly decreased
- but: the number of rainy days has decreased
- and: the intensity of precipitation per day has increased
- causing both severe droughts and floods
- More intense changes when you look at a shorter amount of time (right)
- Really dramatic is the way it rains: same amount in few days
- more drought and flood is created
- dramatic alternations called “tropicalization”
ocean warming
- ocean warming dominates the increase in energy stored in the climate system
- accounting for more than 90% of the energy accumulated between 1971 and 2010 (high confidence)
- It is virtually certain that the global upper ocean (0−700 m) has warmed since 1970s
why are glaciers melting?
mountain glaciers are decreasing due to
1. increase in temperature
2. decrease in rainfall
shows decrease in both graphs
sea level rise
- the rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia (high confidence)
- Over the period 1901 to 2010, global mean sea level rose by 0.19 [0.17 to 0.21] m