Introduction to Meteorology Flashcards
Why is there more CO2 in the atmosphere in May than in October?
- Plants take up the gas in spring and summer by photosynthesis and respiration and release it in fall and winter
- The range is expanded by burning fossil fuels and other human activities, at least the former being more present in winter due to heating etc.
What is a greenhouse gas?
Name 3 greenhouse gases.
- It is a gas that contributes to the greenhouse effect by absorbing infrared radiation
- Carbon Dioxide, Methane, Nitrous Oxide, (Fluorinated Gases)
How does the mysterious “Cloud Edge” form?
- Dry stratospheric air is pulled down into the troposphere. The dry air turns cloud ice crystals directly to gas (sublimation) -> Cloud is dissolved
- Exceptional case! Normally the troposphere and the stratosphere are separated
How does CO2 vary and how does it impact the climate?
- CO2=Trace gas -> Sources+sinks at the surface (land and ocean)
- ±400ppm, but it can reach >2000ppm in polluted cities
- (can inhibit cognitive function indoors)
- It varies over seasons
- reflects black body radiation -> greenhouse gas -> warms the earth
- the warmth has many cascading effects
Where did oxygen come from?
- oxygen slowly builds up (photosynthesis by Cyanobacteria/blue algae) and is mostly taken up by the ocean and sediments
- When these inventories are filled, the atmosphere oxygenates rapidly
- The colonisation of the continents was dependent on the formation of the ozone layer
What are aerosols and how do they influence the Climate?
- Aerosols are suspended solid or liquid particulates (0,1nm - 10 μm)
- removed from the atmosphere either by slowly sinking or washing out in rain and snow
- Equilibrium in the atmosphere by these processes
- Examples: Pollen, dust, soot (black carbon), seas salt, sulphates (SO2, H2S…)
- Direct effect: Reflects radiation (e.g. sulfates) and absorbs radiation (e.g. soot)
- Indirect effect Condensation nuclei for clouds, cloud formation, cloud albedo (more+smaller droplets = brighter clouds), cloud lifespan (smaller droplets dont rain out as fast)
- “Cloud Seeding” possible (Geoengineering) - It stopped it from raining at the Chinese parade
Are aereosols “good”?
In theory:
* Cloud seeding allows us to “control” precipitation”
* Reduces incoming solar radiation, i.e. cools the climate
In praxis:
* A lot of sulphates in the stratosphere would be needed to offset CO2 emissions
* sulphates and soot are bad for human health
* aerosol pollution not a morally decent solution for CO2 pollution
What does the atmosphere consist of?
Nitrogen - 78,08%
Oxygen - 20,95%
Argon - 0,93%
Carbon Dioxide - 0,04%
Other gases - < 0,01%
When the air is not dry, in addition: Water vapor - 0-3%
In which a tmospheric layer is the ozone layer?
Over which region do we typically find the ozone hole and why is it there?
What causes/caused the enlargement of the ozone hole?
- The ozone layer is located within the Stratosphere
- It is situated mostly over the Antarctica
- Ozone is mostly created in the tropics (lots of sun)
- Antarctica is more isolated during the polar light and much colder
- It was/is caused by Chloro-Flouro-Carobs (CFCs)
What are the layers of the atmosphere and how are they organized?
- Troposphere (0-12km) - clouds, planes etc.
- Stratosphere (12-50km) - Ozone layer (20-30km)
- Mesosphere (50-80km) - Star Showers
- Thermosphere (80-700km) - Satellites (Karman line at 100km)
- Exosphere (>700-190000km) Exobase >700-1000km
The Silly Monkeys Twirled Endlessly
What are the different types of climate variabilities?
- El Niño Southern Oscillation (ENSO) - Period ≈ 3-4yrs
Variations in the surface temperature difference between western and eastern tropical pacific ocean and surface air pressure between Tahiti and Darwin
(alternates with La Niña, there are some hints that El Niño -> NAO- (cold winter) and La Niña -> NAO+ (mild winter) - North Atlantic Oscillation - Period ≈ 5-10yrs.
Variations in the air surface pressure difference between Iceland and the Azores - Atlantic Multidecadal Oscillation - Period ≈ 50-100yrs.
Variations in Tropical and North Atlantic Ocean surface temperature - Little Ice Age - 1650-1850
Cold global mean-temperatures. Thames froze over. Swedish Army walked to Copenhagen. Causes not fully settled - Ice Ages - Period ≈ 100.000yrs.
What do the Milankovich Cycles consist of?
- Eccentricity: Shape of Earths Orbit (≈100.000 yrs.)
- Precession: “Wobbling” of spin axis (21.000-26.000yrs.)
- Obliquity: Axial tilt (≈41.000 yrs.)
What feedback mechanisms exist in the climate system?
Lapse-rate feedback
* Tropics: Warming -> more humidity -> more heating at high altitude -> more long-wave radiation to space -> cooling
* Poles: Warming -> more humidity -> stronger greenhouse effect near surface -> warming
Infrared radiation feedback
* Warmer atmosphere radiates more long-wave energy
* Negative feedback
Ice-Albedo feedback
* Bare ice is more reflective than open ocean -> higher Albedo
* Surface warming -> sea ice melts -> darker surface -> warming
* This happens especially in the Arctic because it warms more than the global mean
Cloud feedback
* Clouds are brighter than Earth’s surface -> Negative feedback
* But: Low clouds net cooling, High clouds net warming
Water vapor feedback
* Warmer air can hold more water vapor (greenhouse gas)
* Positive feedback loop
What is the Thermohaline conveyor belt?
- Cold, saline water sinks in the NOrth Atlantic and Southern Ocean
- Ventilation in the Pacific and Indian Oceans
- Warm surface water is transported to the North Atlantic
How long should a time series be before we can estimate the climate?
At least 30 years to adjust for certain variabilities (cold winters, dry summers, hurricanes, heat waves…)
The global-mean surface air pressure is 985 hPa. What is the mass of the atmosphere? (Assume hydrostatic pressure and an earth radius of 6371km)
What does geopotential mean?
The geopotential is the work required to lift a 1kg body from sea-level z=0 to height z.
It is also the potential energy of a unit mass 1kg (referenced to the geoid)
What is virtual temperature?
- Virtual temperature is the temperature at which the gas law for dry air also applies to moist air.
- As Tv>T, as long as q>0 -> moist air is lighter than dry air!
