Groundwater
Volume is 35 times larger than all freshwater lakes and streams
The more time the water spends in contact with a rock, the more mineral constituents will be dissolved from the rock into the water
3 zones of groundwater
Aerated zone
Saturated Zone
Water Table
Aerated zone
Just beneath ground surface, pore space in rock is filled with air
Saturated zone
Pore spare is filled with water
Water table
Upper surface of saturated zone
Percolation
Way in which groundwater flows
Porocity
Percentage of a rock that is open pore spaces
Permeability
Measure of how easily fluids pass through a material
Where does water flow to?
Areas of discharge
Aquifier
A body of rock or regolith sufficiently porous and permeable to store and conduct significant qualities of groundwater
Cryosphere components
Permafrost
Sea ice
Glaciers and ice sheets
Permafrost
Ground that stays frozen >3 years
Active layer (permafrost)
Freezes in winter, thaws in summer
Snowline
Lower limit of perennial snow
Altitude changes from year to year, depending on snow accumulation and summer melt
How do glaciers form and where?
From snow that has accumulated over many years
At high latitudes or high mountains at low latitudes
Glacier
Ice so thick that it flows due to gravity
How do glaciers flow?
Internal deformation
Basal sliding
What determines whether glaciers advance or retreat?
Balance between snow and ice added (accumulation) and lost (ablation)
How does cryosphere affect the earth system
Reflecting ice and snow reduce surface temperature
Snow and glacier melt are major sources of water for people and moisture for soils
Parts of biosphere depend on meltwater, snow, or ice
Influence on ocean salinity
Melting ice sheets -> sea level increase
Atmosphere
Gaseous envelope that surrounds a celestial body
Air
Mixture of gases and particles that surrounds the Earth
Primordial atmosphere
Made after accretion, eventually stripped away by solar winds
Secondary atmosphere
Volcanoes outgassed light elements and formed secondary atmosphere
Composed of water vapor, methane, hydrogen, nitrogen, CO2, and argon
Oxygen then and now
Virtually none 4 billion years ago now 21%
Almost all came from photosynthesis
Ozone
Buildup of O2 cause increase in ozone
Absorbs harmful UV, made it possible for light to flourish
Composition of modern atmosphere
78% N2, 21% O2, 1% Argon, .04% other
What drives global atmospheric circulation?
Pressure/temperature gradients
Coriolis force from Earth's spin on its axis
Hadley Cells
Equator to 30 degrees in either direction
Warm air rises in the tropics
Air piles up at 30 degrees, creating sinking, high-pressure air
Generate westerlies and trade winds
Monsoons
Seasonally reversing wind systems
Driven by temp contrasts between land and sea
Winter: high pressure over cold land and low pressure over ITCZ cause cool, dry cloudless days (rain over sea)
Summer: low pressure over hot land, high pressure over ITCZ, cau
Weather vs. Climate
Weather: state of the atmosphere at a given time (Temperature, air pressure, humidity, cloudiness, wind speed, and direction)
Climate: an averaging out of that over long periods of time
What can change climate?
Internal oscillations
Mean state
Internal oscillations
<10 year timescales (El Nino)
Regional trends, not global
Mean state
Changes in Earth's energy balance
Global, can be short or long term
Must have a cause (a "forcing")
First law of thermodynamics
Energy going in = energy going out
Incoming radiation (type and source)
Short wave
How much energy the Sun emits
How much of it the Earth absorbs
What changes solar intensity?
Over billions: solar evolution (faint young Sun paradox)
10,000s: Earth's orbit and tilt (ice ages)
Decades: sunspot cycles
Outgoing radiation
Greenhouse effect
Incoming radiation reflected as IR
Some escapes to space, some is absorbed by GG
Ozone
Depleting in the stratosphere
Protects us from harmful UV
UV rays can: weaken immune system, produce cataracts, increase frequency of skin cancer, cause genetic mutations
What destroys ozone?
Chlorine
"Ideal" in: Antartica in spring
-Sunlight arrives, cold enough to form polar stratospheric clouds
Ground level ozone
Component of smog
Direct contact is harmful to plants and animals
Forms when NO2 gases from emissions react with volatile organic compounds with help from heat and sunlight
Water table flow
From areas where water table is high toward where it is lowest, in response to gravity and pressure gradients
Recharge
Replenishment of groundwater
Subsidence
Decline of a water table in which the land depresses and collapses
Palioclimate sheets
Ancient ice and ancient air preserves in ice sheets
Zone of accumulation
Where a glacier gains mass, high part of the glacier/upslope
Zone of ablation
Where a glacier loses mass, downslope and losing snow
Equilibrium line
Altitude where accumulation = ablation
Terminus
The front of a glacier. Advances as it grows, retreats as it loses mass
Internal deformation
When ice reaches a critical thickness, the mass begins to deform and flow downslope under the pull of gravity
Occurs in deeper parts of glacier
Basal sliding
Ice temperature is very important in controlling rate of movement
Meltwater at the base of a temperate glacier acts as a lubricant and permits the ice to slide across its bed
Changes in glacier profile
Not much because ice is continuously being transferred from the accumulation area to the ablation area
Calving
Progressive breaking off of icebergs from the front of the glacier that terminates in deep water
Sea ice
Consists of fresh water
Salinity and sea ice
When more sea ice is formed, the ocean becomes saltier
When it melts, fresh water is released and the ocean is less salty
Positive feedback loop of ice
Increased ice = higher albedo = greater sunlight reflection = further cooling. Other way around for melting
Spheres from ground to universe
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere
Insolation
Energy that actually reaches a surface
Troposphere
Endlessly convecting
Temperature decreases with altitude
Absorption of radiation is most effective where air is most dense
Stratosphere
Temperature increases with atmosphere
Presence of ozone
Less UV is absorbed the further down you go AKA less warmth
Mesosphere
Temperature decreases with increasing altitude
Coldest layer
Does not contain ozone so radiation passes through without warming
Thermosphere
Temperature increases increases with altitude
Reaches the highest temperatures of any layer of Earth's atmosphere since it is closest to the sun (gas molecules bombard and absorb)
Coriolis force
Deviation from a straight line of path due to EArth's rotation
Causes a deflection of the path of the moving object toward the right in the NH and the left in the SH
Causes of internal oscillations
Atmospheric filtering
Changes in albedo
Volcanic CO2
Milanjovitch cycles
Changes in the axis of rotation, tit of Earth's axis, and eccentricity of Earth's orbit
Ice sheets + CC
Not a good indicator
Bad models
Glaciers and ice caps + CC
Less water than ice sheets but melt quicker
Sea Ice + cc
Huge increase in summer melt
Permafrost + CC
Active zone getting thicker over the years
Ocean + CC
Ocean is poorly sampled but warming
No evidence currents are changing
Carbon content has increased, taking CO2 from the atmosphere