Unit 3 Test Flashcards
What is the typical lifecycle of a single-cell thunderstorm?
Approximately 30 minutes
What is a downdraft and why does it occur?
Rapidly sinking air caused by precipitation, which helps cut off the rising motion of single-cell thunderstorms
What is a mesoscale convective system?
Group of “cells” of thunderstorm, with each being from 30-60 minutes and the whole system lasting several hours, which is overall typically more intense than a single-cell thunderstorm
What are the two types of mesoscale convective systems?
Squall-lines and mesoscale convective complex (MCC)
What is a squall-line?
A line of thunderstorms formed along or out ahead of a cold front
What is a mesoscale convective complex (MCC)?
A circular-shaped, self-sustaining system of thunderstorms
Why are tornadoes so common in the central and southern US?
We have all the “ingredients” - weather systems with fronts, unstable air, and lots of vertical wind shear
What time of the year do tornadoes most frequently occur?
March-June
How does hail form?
- A frozen water droplet is swept up by currents within a thundercloud
- Supercooled moisture freezes onto the droplet’s surface forming a layer of ice
- As it gets heavier, gravity pulls it downward
- Then it’s sucked back up by strong updrafts
- As the process continues, thick layers of ice accumulate on the hailstone’s surface
- Eventually, gravity pulls the hail through the warm, wet cloud base and finally to the ground
What are the stages involved in lightning formation?
- Potential difference - A buildup of negative charge at the base of a thundercloud creates a positive charge region on the ground
- Stepped leader - A channel of negative charge moves from the cloud to the ground in a series of steps
- Streamer formation - Positive charges move upward from the ground toward the cloud
- Return stroke - The stepped leader and streamer meet, creating a conductive channel that allows a large electric current to flow from the cloud to the ground, which is the visible lightning flas
- Short circuit - The high-temperature conducting channel short-circuits to the ground
- Final stage - The channel continues to transfer charge to the ground, but less intensely
Describe the spiral rain bands of tropical cyclones?
Curved bands of clouds and thunderstorms that trail away from the eye wall in a spiral, often producing heavy rain and wind, or even tornadoes
Describe the eye of tropical cyclones?
The center of the storm, which is an area of sinking air and light winds, making up the calmest part of the storm
Describe the eye wall of tropical cyclones?
An area around the eye of the storm consisting of a ring of tall thunderstorms producing heavy rain and the strongest winds
Why is the front right quadrant of a hurricane important?
High wind speeds, storm surge, and tornadoes are all maximized in this area
What is storm surge and where is it the greatest?
Ocean waters that pile up ahead of the hurricane due to the storm’s net winds, which is greatest to the right of where the winds are the greatest
How do volcanoes impact climate over the short term?
Atmospheric cooling due to the injection of aerosols, which raise global albedo, reflecting solar radiation into space and cooling for a year post-eruption
How do volcanoes impact climate over the long-term?
The long-term effect is warming because volcanoes do emit greenhouse gases (but they aren’t a significant contributor to current climate change)
How does solar output impact climate?
Earth’s temperatures are linked to variations in the amount of energy emitted by the Sun, reflected in sunspot activity, but this has been declining in recent decades even as temperatures continue to rise, so it is not a cause of global warming
What are the two Milankovitch cycles?
Eccentricity and precession
What is eccentricity Milankovitch cycle?
Describes variattions in how elliptical Earth’s orbit is, which varies in ~100,000 year cycles. Low eccentricity = little variation in the earth-sun distance; high eccentricity = up to 20% difference in solar radiation between perihelion and aphelion
What is precession Milankovitch cycle?
Describes the wobble of Earth’s axis like a top, which varies in ~26,000 year cycles. Currently, the Northern Hemisphere is tilted away from the sun during the perihelion [closest point in orbit to sun]; eventually the Northern Hemisphere will point toward the sun during the perihelion
How is the recent period of global warming different than past periods of warming, and how do we know it’s not due to the discusses natural sources of climate change?
Our climate has changed before, but our role is new. Based on Milankovitch cycles, we should be starting a long, gradual decline into another ice age, and natural sources of climate variability do not account for this warming trend
What is the cause of the recent period of global warming?
The main cause is humans changing the atmospheric composition since the Industrial Revolution by adding greenhouse gases
Who was Eunice Foote?
She first saw the effects of selective absorption by greenhouse gases (in 1856)
Who was John Tyndall?
He first documented the effect of greenhouse gases by capturing gas emitted during the combustion of coal in a glass tube and finding that it was a powerful absorber of infrared energy (in the 1860s)
Who was Svante Arrhenius?
He calculated the influence of CO2 emissions on global temperature (doubling of CO2 leading to an increase of 5 degrees C; today’s estimate is closer to 1.5-4.5 degrees C), thinking it would be beneficial to warm colder regions (in the 1890s)
What is a positive feedback loop?
Increases the initial change, moving away from equilibrium and producing instability (ex: ice-albedo and water vapor feedback)
What is a negative feedback loop?
Decreases the effect of change, moving away from equilibrium and maintaining instability (ex: regulation of temperature through cloud cover)
How has the sea level changed in recent decades, and why?
Has increased by ~4 inches since 1993 due to the melt of grounded ice (glaciers + ice sheets) and the subsequent runoff
What are the leading sources of anthropogenic greenhouse gases?
Mainly due to the use of fossil fuels due to cars, heating buildings, and power factories
Which economic sectors contribute the most to global emissions?
Transportation, electric power, and industry
What are the nuances of which countries contribute the most to greenhouse gas emissions?
China looks to lead it by far, but looking by capita is actually in 7th place, with US, Canada, and South Korea leading. Much of China’s carbon emissions are also to satisfy the “appetite” of western countries
Define uniformitarianism?
The same physical processes active in the environment today have been operating throughout geologic time; “The present is the key to the past”
What are endogenic processes?
Encompasses internal processes that produce flows of heat and material from deep below Earth’s crust; radioactive decay is the main energy source (Ex: tectonics, earthquakes, and volcanism)
What are exogenic processes?
Involves external processes that set into motion air, water, and ice, all powered by solar energy (Ex: Rivers, landforms, weathering, erosion, oceans, and glaciers)
What is the order of the Earth’s interior layers?
Inner core, outer core, mantle, crust (innermost to outermost)
Describe the pattern of density of the layers of the Earth’s interior?
The inner core is extremely dense, with density decreasing as you move outward
Are the layers of the Earth’s interior liquid or solid?
Inner core - solid, outer core - liquid, mantle - solid, crust - solid
What is responsible for the generation of the Earth’s magnetic field?
The outer core, which flows as the Earth spins, generates the Earth’s magnetic field because it is made of liquid molten metallic iron. Its strength and orientation vary, and it reverses itself every ~500,000 years
What is the lithosphere?
Made up of the crust and uppermost mantle, is 50-100 km thick, and litho = rock because it’s brittle and “breaks”
What is the asthenosphere?
Only the mantle, is ~250 km thick, and astheno = “w/o strength” because it’s ductile and bends
What are minerals?
Naturally occurring, inorganic, solid, crystalline structure, and definite chemical composition
What are rocks?
Naturally occurring aggregates of minerals (1 or more)
What are the three main rock types and their subtypes?
Igenous (extrusive or intrusive), sedimentary (clastic or chemical), and metamorphic
How are igneous rocks formed?
From molten rock which becomes magma
What’s the difference between extrusive and intrusive igneous rocks?
Extrusive rocks form at the surface due to eruptions and volcanic activity, are fine-grained, and cool rapidly, while intrusive rocks are formed underground, are coarse-grained, and cool and solidify more slowly
How do sedimentary rocks form?
Through lithified sediment; composed of grains
What’s the difference between clastic and chemical sedimentary rocks?
Clastic are formed from particles (or clasts) that are eroded from other rocks and deposited (can range anywhere from coarse to fine), while chemical are formed from minerals precipitated from solution, which occurs in bodies of water, such as lakes or oceans
How do metamorphic rocks form?
Recrystallization of other igneous, sedimentary, or metamorphic rocks to a different mineral structure under great heat and pressure; higher density; more resistant to weathering
What is foliation?
A repetitive layering pattern of buildup seen in metamorphic rocks
What are the evidences of plate tectonics and how do they support the theory?
Signs of continental drift are seen in how continent shapes fit together like a puzzle and alignment of fossils across continents
What type of earthquake activity is associated with subduction zones?
The deepest earthquakes occur along subduction zones, and we can see a progression from shallow to deep earthquakes along subduction zones
What is rifting?
Rifting is the extension/spreading of plates (divergent plate boundaries)
What landforms are associated with continental and oceanic rifting?
Oceanic rifting creates mid-ocean ridges, while continental rifting creates valley dividing continents and new ocean basins
At what plate boundaries does subduction occur?
Subduction occurs at oceanic-oceanic and oceanic-continental convergent plate boundaries (very little or none at continental-continental convergent)
What features are present along subduction zones?
One plate being pulled under another is what occurs along subduction zones, along with deep earthquakes. Oceanic-oceanic creates ocean trenches and volcanic activity above surface, and oceanic-continental creates volcanic activity on land
Is there volcanic activity at subduction zones and, if so, what type (effusive vs explosive)?
Volcanic activity is present at rifting/subduction plate boundaries, specifically explosive types (the typical volcano type you think of – more explosive; forms new continental ground; steep-sided volcanoes due to interlayered ash and lava; pyroclastic flow and lahars)
