-
Weather
Short-term, day-to-day condition of the atmosphere
-
air masses
a homogenous body of air that has taken on the temperatures and moisture characteristics of its source region
-
-
Air masses-Temperature
- A-Arctic
- P-Polar
- T-Tropical
- E-Equatorial
- AA-Anarctic
-
cP
- cool, dry, stable, high pressure, clear skies
- Only in the northern hemisphere
- most developed in winter
- in mid and high latitudes
- cold, dense cP air lifts moist, warm air in its path
-
-
mT
- warm, humid
- Gulf/Atlantic-unstable winter to very unstable summer
- Pacific-stable to unconditionally stable, lower avg precipitation
-
cT
hot, low humidity, only in summer in USA
-
atmospheric lifting mechanisms
- convergent lifting
- convectional lifting
- orographic lifting
- frontal lifting
-
convergent lifting
- air flows from different directions into the same low pressure area
- along the ITCZ-cumulonimbus cloud development; high avg annual precipitation
-
convectional lifting
- stimulated by local surface heating
- urbanized area-heat island
- dark soil in a plowed field
- If the conditions are unstable, initial lifting continues and clouds develop.
-
orographic lifting
- air is forced over a barrier ie) mountain range
- lifting air cools by expansion
- enhance convectional activity
- cause additional lifting during the passage of weather fronts
- creates dry regions leward of mountain
-
Cold front
formation of a narrow line of showers when enough moisture is present
-
squall line
- created by a fast-advancing cold front and its violent lifting
- wildly changing and turbulent winds patterns
- intense precipitation
- ie) Gulf of Mexico
-
Warm front
Temperature inversion-->poor air drainage
-
midladitudinal cyclonic systems
- the conflict between contrasting air masses
- migrating lower pressure center with converging, ascending air spirals inward counter-clockwise in the northern hemisphere
- results from PGF, Coriolis effect and friction force
- movement controlled by jet streams
-
thunderstorms
- 3 places they develop
- 1. in a warm, moist air mass
- 2. along a cold front or dryline
- 3. orographic lifting (upslope winds)
-
dry line (squall??)
a boundary that separates a warm, moist air mass from a warm, dry air mass
-
severe thunderstorm
- 3/4 inch hail or surface gusts of 58 mi/hr winds
- formation-updrafts tilt
- Result--high winds, flash floods, hail, tornadoes, down bursts
-
downbursts
- a column of air that, after hitting ground level, spreads out in all directions and is capable of producing damaging straight-line winds of over 150 mph
- damage similar to tornadoes
-
tornadoes
- severe or super-cell thunderstorm
- 100-600 meter diameter
- winds up to 300 mph
-
tropical cyclones
- hurricanes between 5 and 20 degrees of the equator
- too close to equator-no coriolis
- too far from equator-water is too cold
-
Recipe for hurricanes
a mild disturbance (Easterly wave) in the tropics
- deep layer of warm water
- limited vertical wind shear
- upper-level divergence
-
Hurricanes
- strong, low pressure (870-990mb)
- inward flow of rising air
- inward spiral of cloud bands
- well-defined eye wall
- weak descending air in the eye
move from east to west in the tropics and curve NE as they move into the midlatitudes
Season- June 1st thru November 30th
-
impact of hurricanes
- widespread flooding
- high winds
- storm surge
- tornadoes
-
storm surge
- large wall or dome of water that rushes into the coastline as a result of a hurricane making landfall
- combo of the wind-driven (more significant) surge and the pressure surge
-
hydrologic cycle
- an elaborate and global plumbing system
- operated for billions of years from the lower atmosphere to several km beneath earth's surface
-
reservoirs in the hydrologic cycle
- atmosphere
- oceans, lakes, rivers
- soil
- glaciers and snowfields
- ground water
-
main processes of the hydrologic cycle
- evaporation
- transpiration
- condensation
- precipitation
- infiltration
- percolation
- runoff
-
Pathways of precipitation
- flow overland
- soaks into soil
-
interception
when precipiation strikes vegetation or other ground cover
-
stem flow
- intercepted rain that drains across plant leaves and down their stems to the ground
- important moisture route to the ground surface
-
throughout flow
precipitation that falls directly to the ground plus precipitation that drips onto the ground from vegetation (excluding stem flow)
-
infiltration
through which water soaks into the subsurface
-
percolation
through which water permeates soil or rock through downward movement
-
long residence
- 3000-10,000 years
- deep ocean circulations, groundwater aquifers, glacial ice-->moderate temperatures and climatic changes
- LONG SYSTEM MEMORY
-
short residence
- about 10 days
- temporary fluctuations in regional weather patterns
- SHORT SYSTEM MEMORY
-
soil-water budget
precipitation = actual evapotranspiration + surplus +/- soil moisture storage
PRECIP = (POTET - DEFIC) + SURPL +/- STRGE
-
evapotranspiration
evaporation plus transpiration
-
-
transpiration
cooling mechanism in plants through evaporation
-
POTET
- potential evapotranspiration
- the amount of water that would evaporate and transpire under optimum moisture conditions when adequate precipitation and soil-moisture supply occur
-
Surplus
- sits on the surface in ponds, puddles, and lakes
- flow across the surface toward stream channels-overland flow
- percolate through the soil underground
-
soil-moisture storage
the volume of water stored in the soil that is accesible to plant roots
-
hygroscopic water
a molecule-thin layer tightly bound to each soil particle by the hydrogen bonding soil molecules
-
capillary water
to plant roots, held against the pull of gravity
-
groundwater
- important part of the hydrologic cycle
- lies beneath the surface-beyond the soil-moisture zone
- the largest potential (available) freshwater source
- Threats: pollution-related water quality, overconsumption
- NOT an independent source of water; relies on surfaec supplies for recharge
-
Ocean and Freshwater Distribution
-
water table
top of ground water layer
-
zone of saturation
pores are completely filled with water
-
zone of aeration
soil and rock is less than saturated
-
aquifer
rock layer that readily holds water
-
aquiclude
a body of rock that does not conduct water-->impermeable
-
artesian water
groundwater that is confined under pressure
-
potentiometric surface
the pressure level to which water can rise on its own
-
how much of earth's surface do continents cover?
29%
-
inner core
solid iron-under tremendous pressure
-
outer core
molten, metallic iron with a lighter density than inner core
-
lithosphere
uppermost mantle-the crust
-
asthenosphere
- the plastic layer-dynamic pockets of increased heat from radioactive decay
- susceptible to slow convective currents
-
crust
- irregular, brittle layer that resides restlessly on a dynamic and diverse interior
- the weak nature of the rock allows for motion in earth's rigid outer shell
-
Oceanic crust
- thinnest
- Basalt
- high in density
- SIMA-silica and magnesium
-
continental crust
- thickest
- granite
- SIAL-silica and aluminum
- low in density
-
isotasy
crust is constantly rising and sinking
-
endogenic system
- internal
- building landforms
-
exogenic system
- external
- tearing down landforms
-
tectonic cycle
- brings the heat energy and new materials to the surface and recycles old materials to mantle depths
- creates movement and deformation of the crust
-
Plates are adrift because of....
convection currents
-
process response model
how we understand most geomorphic processes today
-
plate tectonic processes
- upwelling of magma
- plate movements
- folding (warping)
- faulting (shearing)
- earthquake activity
- volcanic activity
-
divergent boundaries
- where plates move apart
- spreading center
- zones of tension
- creates fractures as the plates move apart
- filled with molten rock
- producing new slices of crust
- results in rift valleys and seafloor spreading
-
convergent boundaries
- where plates move towards each other
- collision zones, compression and crustal loss
- causing one of the plates to sink into the asthonesphere by descending beneath the other
-
-
Oceanic-Oceanic
- subduction zone and deep ocean trench
- subducting oceanic plate melts and rises; volcano forms on ocean floor
- can lead to island arcs-chain of volcanic islands
- ie) the Alaskan Peninsula, Philippines, and Japan
-
Continental-Continental
- when two continental plates converge
- none will subduct (due to their low density)
- collision between the plates
- ie) Himalayas, Urals, Alps, Appalachians
-
transform boundaries
- when the plates slide past each other
- neither convergance or divergence
- no volcanic eruptions
- primarily earthquake activity
-
Evidence for plate tectonics
- hot spots
- ie) Hawaiian chain of volcanoes, Yellowstone, Kaual (oldest)
-
Whether a rock bends or breaks depends on....
- composition
- deformation-ductile or brittle
- gentle, slow, ductile-->folding (bending)
- violent, abrupt, brittle-->faulting (tearing)
-
folding
- anticline: upholding, arching
- syncline: downfolding, trough
-
differential weathering
- rocks of different strength will break down at different rates
- over time the resistant rocks become highs and softer rocks become lows
-
faults
fractures in the crust along which appreciable crustal movement has occurred
-
dip-slip fault
- normal-tension
- reverse-compression
-
strike-slip fault
- movement along the fault plane is horizontal
- ie) San Andreas, North Anatolian Fault System
-
Faults in concert
- a roughly parallel series of faulted mountains and valleys
- ie) Great Rift Valley of East Asia, Death Valley, Rhine Garden
-
earthquakes
vibrations in earth from sudden release of energy, radiates through the crust and diminishes with distance
-
focus
sub-surface area along a fault plane where motion is initiated
-
epicenter
area at the surface directly above the focus
-
aftershock (foreshock)
shock that occurs after (before) the main shock
-
P waves
- push-pull motion
- travel through any material
-
S waves
- up-down/side-side motion
- travel only through solids
- shake the ground surface and can do severe damage
-
surface waves
- travel slower than S and P waves
- cause much of the damage near the epicenter
- rolling motion-cracks the walls and foundations
-
Moment Magnitude Scale
- modified version of the Richter scale
- each increase of 1 represents a 10-fold increase in wave amplitude and 31.5-fold increase in the total amount of energy released
-
liquefaction
intense shaking can cause a near surface layer of water-saturated sand to change rapidly from a solid to a liquid
|
|