geology unit 3

what is climate?

study of climate is study of how the Sun’s energy is trapped and transported across the Earth

radiative balance

Earth heats up enough so that it emits as much radiation as it absorbs

albedo

reflected solar radiation

when does earth stop warming

when achieves radiative balance with solar and back radiation

main component of Earth’s atmosphere

nitrogen

what does all liquid water do better than air

transports heat

el nino

warm sea surface temperature in eastern equatorial pacific

where is warm water during el nino and why

near south america, NE and SE winds aren’t carrying warm water to indonesia

continents heat up and cool down more than

oceans

do injected particles from volcanism result in heating or cooling and why

cooling because they block the sun’s radiation

plants influence

albedo

what does high eccentricity look like

earth revolves around the sun in a more oval shaped path 

what does low eccentricity look like

earth revolves around the sun in a more spherical shaped path

what drives the climate system

heat from the sun

how is heat transferred from the equator to the poles

wind and ocean currents

tilt

precession

weathering

breakdown and fragmentation of rocks

erosion

removal of weathered material from its source

mass wasting

collapse of hillsides

chemical weathering

minerals in a rock dissolve or undergo chemical alteration in the presence of water and/or air

physical weathering

rocks and the minerals are mechanically fragmented without a change in chemical composition

chemical weathering works faster with

more surface area

what is the influence of silicate weathering on CO2

removes CO2 from the atmosphere and works to form shells (CaCO3)

soils

the residue of chemical weathering

factors that influence soil formation

time, climate, topography, parent material, and organisms

why does most chemical weathering on Earth occur in soils?

soils retain water and remain wet at depth long after surface dries out. plants and microorganisms in the soil produce acids which help chemically weather minerals in the soil

rocks must be broken down before they can

be removed by water, ice, or wind

soils form when

material is removed by chemical weathering

fine sand angle of repose

35

coarse sand angle of repose

40

angular pebbles angle of repose

45

reservoir

storage place for water

hydrologic cycle

models the movement of water from one reservoir to another (means and amount)

relative humidity

amount of water vapor in the air (warm air can hold more than cool air)

when warm air cools, it can become supersaturated and water condenses to form

clouds

most precipitation occurs in louisiana and florida range and progressively decreases as

you go west, with the exception of pacific northwest

runoff map

half the global runoff is carried in 70 largest rivers and half of that is 

carried in the Amazon alone

runoff surface storage (reservoirs)

lakes, wetlakes

what do dry periods mean for amount of runoff

low runoff

what do wet periods mean for amount of runoff

high runoff

with high runoff during wet periods, some water is stored and slowly released during

dry periods

water table

boundary between unsaturated zone (vadose zone) and saturated zone (phreatic zone)

groundwater

part of subsurface water that is in the saturated zone

porosity

percent rock volume that is pores - defines the amount of water a volume of rock can hold

porosity increases with

increased sorting

porosity is independent of

grain size

permeability

interconnectedness of pores

permeability decreases with

decreasing grain size, porosity, and sorting

infiltration

surface water infiltrates into the unsaturated zone by gravity and capillary forces and moves into the water table

hydraulic head

elevation of a water table above a particular location-usually sea level

groundwater moves by

gravity and pressure difference along a head gradient

groundwater moves from

high head to low head (not always downhill)

recharge

addition of water that causes the water table to rise (increased evaporation or withdrawal by pumping lowers the water table)

cone of depression

water is pumped faster than it can recharge

aquifer

any permeable, saturated layer that can transport water

aquitard

an impermeable layer that prohibits flow of water

unconfined aquifer

upper boundary defined by the water table

confined aquifer

upper boundary is an aquitard

springs

ground water discharge feature that form wherever the land surface intersects the water table

knowing how the water flows in the aquifer can help

planners protect our water supply and places like Barton Springs

the rate of groundwater use in the U.S. today greatly exceeds

the rate of recharge

laminar flow

flow lines are parallel and do not mix

turbulent flow

flow lines cross and mix chaotically, most rivers and streams

laminar flows have

low velocity, high viscosity, and shallower channels

turbulent flows have

high velocity, low viscosity, deeper channel, and high sediment load

suspended load

fine-grained sediment (typically clay and silt) transported in suspension due to turbulence

bed load

coarser-grained sediment (typically sand and gravel) transported on bottom of stream bed by rolling and sliding

saltation

sediment (typically sand) transported by intermittent jumps - a transitional state between bed load and suspended load

competence

ability to carry material of a given size

capacity

total sediment load

velocity and volume of a flow affect

both competence and capacity

as velocity increases… (dunes and ripples)

flat bed → small ripples → dunes → ripples form on dunes → flat bed (dunes washed away)

ripples and dunes migrate

downstream

stream valley

area between the tops of the slopes on both sides of the river

channel

trough through which the water runs

floodplain

flat area either side of the channel where water overflows during floods

meandering is common in

flat areas

meandering stream

low sediment load, low velocity

max velocity on the outside edge of meandering stream

max erosion

low velocity on inside edge (deposition)

point bar

braided stream

high velocity and high sediment load

braided stream channel patterns depend on

flow velocity and sediment load

drainage basin

area that funnels water into network of interconnected streams

divide

ridge that separates two basins - runoff flows down either side of the divide

antecedent streams

established before a tectonic event uplifts the rock → deeply cut stream channel

superposed stream

erode through resistant rocks after their stream channel has been established on younger flat lying rocks

discharge

volume of water that passes a given point in a given time through a channel of a certain width and depth

discharge formula

width x depth x velocity

discharge generally increases

downstream

increased discharge means

width, depth, or velocity must increases too (velocity generally doesn’t increase downstream)

dynamic equilibrium 

balance between erosion of the streambed and sedimentation in the channel and floodplain

dynamic equilibrium balance depends on

topography (slope), climate, streamflow (discharge, velocity), resistance of rock to weathering and erosion, sediment load

longitudinal profile

plot of elevation vs. distance along a stream

• profile typically becomes flatter as elevation decreases

• the lower level of the profile is controlled by base level (ocean or lake)

floods occur when

the discharge exceeds the capacity of the present channel to accommodate the flow

flooding is

normal and expected event on all rivers when input exceeds the discharge capacity

river engineering (straightening river channels) can make floods worse by

removing natural protective mechanisms

floods are the

leading cause of natural disaster deaths worldwide

floods can cause stream/river to build up

natural levees after many floods