Flashcards in Circulation of the Upper Atmosphere and Oceanic Circulation Deck (44)
High Pressure often causes a Temperature Inversion. How?
The TI is a “cap” (layer) of warm air atop cooler air that keeps air from rising, cooling, and precipitating. Sinking air from STH is warming, while air near surface is sometimes cooler especially at night or over water
What does surface temperature inversion mean?
What does lack of condensation/ rainfall create?
What is upper troposphere air flow primarily ?
Westerly air flow from subtropics to polar front. Two jet streams
How many jet streams are per Hemisphere?
2 Jet streams per hemisphere
What is the Polar Jet and what does it affect?
is a narrow ribbon of high speed winds in upper ATM 100–300 miles wide and up to a mile thick. The Polar Jet affects mid-latitude weather.
What is the Subtropical Jet
The Subtropical Jet is not as strong because there is less temperature and pressure contrast
What does the Polar Jet stream separate?
Polar Jet Stream separates cold and warm air masses
What can jet stream wind speeds exceed?
Where does the polar jet stream occur?
The Polar Jet Stream occurs where pressure and temp gradient is greatest
How does the polar jet stream cycle?
The Polar jet cycles from nearly ZONAL flow (parallel to latitude) to an UNDULATING pattern and back again over several weeks
When is the polar jet stream fastest?
In the winter
What do undulating waves do?
Undulating waves develop in the Polar Front that bring cold air equatorward and warm air poleward.
How many undulating waves may be present on the earth at one time?
There may be 3-6 present on earth at one time.
What does strong wind development produce?
Strong wave development produces Low and High pressure cells that move across the mid-latitudes: Mid-latitude cyclones
What do low pressure troughs do?
Low pressure “troughs” steer “tongues” of cold air into mid-lats
Why are oceans important?
Oceans are reserves of energy that help power global weather
How to oceans transfer energy?
Oceans transfer energy from overheated tropics to underheated poles
What are ocean currents like?
Ocean currents are more-or-less continuous or permanent directed movement of ocean water
What factor/force mainly drives ocean surface currents?
Wind. Surface currents reflect average wind conditons
How does surface ocean currents flow?
Surface ocean currents (upper 400 m) flow in loops or gyres that follow STH circulation,
What do continents do to ocean currents?
Block free flow
What does Deep Ocean Circulation do? What is it important to?
Deep Ocean Circulation (Thermohaline) acts as a “giant conveyor belt” that transports heat toward poles. Important to regional climate.
What drives deep ocean circulation?
What are the Younger Dryas and what may have caused them?
The Younger Dryas, a return to glacial conditions occurred about ~12,000 yr BP) long after warming (interglacial conditions) had begun (~18,000 yr BP). Likely related to decreased or halting of thermohaline circ and negative feedback
Could warming cause cooling again, like in the little ice age?
Some models predict 5-9°F cooling in N. Atlantic region if conveyor shuts down
Where are the strongest surface currents?
The strongest surface currents are on west sides of oceans, where water piles up, e.g., Gulf Stream
What happens on E. sides of ocean where surface water is leaving the coast?
Cold water upwelling
How does cold water upwelling work?
Surface water moves AWAY from west coasts, UPWELLING of COLD water into that space
How does cold water upwelling affect climate and vegetation?
Cold water surface chills air above it, causing condensation, fog (more about condensation next week) sometimes the fog moves over land but no rainfall. COLD air cannot rise! Deserts form.
What are some major areas of cold upwelling and dry condition?
Coastal Chile/ Peru, and Namibia
What does very strong cold water upwelling cause?
What are some other effects of cold upwelling?
Upwelling of cold water increases nutrient availability near the surface, supports plankton (bottom of food chain)
What are some biological effects of cold water upwelling?
If there is high nutrient availability in the ocean then there will be large fish populations, and lots of fish eating birds. Lots of fish eating birds produce lots of bird shit.
What is "El Nino"?
Unusually warm surface water in the equatorial Pacific that lasts 1-2 years
When does El Nino occur?
It occurs every 2-7 years (about 30 times per century)
Why is it called El Nino?
It is simplified Nino for "Southern Oscillation - ENSO
What is walker circulation?
Walker circulation (normal condition): Normally, water piles up in western Pacific due to easterly currents; sea level is about 40 cm higher in Australia/Indonesia
What are El Nino Conditions?
El Niño Conditions: Pressure gradient between E. & W. Pacific weakens and Easterly Trade winds relax or reverse! Cold upwelling ceases and piled up warm water in W. Pacific sloshes back to east causing increased rainfall in an otherwise dry region.
What are the climatic effects in the normally arid tropical eastern pacific region (south america)?
• Heavy rain
• Mudslides along coasts that are usually very DRY with sparse vegetation
• Major fish die off because the water is too warm
What are the climatic effects in the normally wet western pacific region (SE Asia, Indonesia, Australia)
What are El Nino Effects around the globe?
Unusual weather patterns around the globe
How do climatic effects of ENSO (el nino) vary?
Climatic effects of ENSO around the globe vary by place, season, episode intensity AND coincidence of other major climatic oscillations such as North Atlantic Oscillation (NAO) and Pacific Decadal Oscillation (PDO)