Earth Sciences– Exam 3
Formation of the Atmosphere

-Took the appearance of life on Earth to add oxygen

-Oxygen formed the ozone

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-Earth’s atmosphere today consists mostly of volcanic gas modified by interaction with sunlight, land, and life

 

Atmosphere of Other Planets Compared to Earth
Very thin
Atmosphere layers in order
Earth’s Surface
Troposphere
Stratosphere
Mesosphere
Thermosphere(Ionosphere)
Troposphere
Starts at Earth’s surface and rises 5km
Known as the weather layer
Stratosphere
Temperature remains and stable and stratified
Ozone is in this layer
Mesosphere
Temperature decreases with height throughout
Thermosphere
Very little gas
Very hot
Reflects radio waves back to Earth
Stops UV light and heat (unique to Earth)
Homosphere
Because the troposphere, stratosphere, and mesosphere have essentially the same gas composition
Why is Earth’s atmosphere unique?
It sustains life
Venus’s atmosphere is very hot and heavy (would crush us)
Mars’s atmosphere is very thin
Atmospheric Composition
Nitrogen– 78.08%
Oxygen– 20.95%
Trace gases– .97% (greenhouse gases important for regulating Earth’s temperature)
Density of Air
The lower you are in the atmosphere the heavier you are because more vapor is weighing down on you

Warm air rises
Cool air sinks

Water Vapor Holding Capacity
Water holding capacity is a function of temperature
Precipitation is initiated by cooling of air because warm air can hold more vapor than cold air
Trace Gases– What are they?
CO2, CH4 (methane), greenhouse gases
O3 (ozone), radon
Aerosols and pollutants
Movement of Air
Moves from high pressure to low pressure (Convection Cell)
Creates Wind
Rotation of planet causes air to move
Heat Distribution– Why is the planet unevenly heated?
Planet rotation
Curved surface of the planet
Travels around the sun
Tilted
Hadley’s Theory– Why it was wrong?
Did not factor in the rect that the Earth rotates
Coriolis Effect
Earth Rotation
Anything traveling towards the pole will be effectively deflected East
Travel towards the Equator deflects to the West
Diverging Winds
A place where air separates into 2 flows moving in opposite directions

Air sinks, and we have high pressure

Converging Winds
A place where 2 surface air flows meet so that air has to rise and create low pressure
Weather
The state of the atmosphere at a specific place and time
Climate
The long-term average of weather in an area
Air Masses
Named after where they form
Changing air masses can change local weather
Warm Front
Warm air goes over cold air horizontally
Cold Front
Warm air tries to go through cold front but ends up going straight up and rising
Monsoon Patterns
Follow the Interconverging zone (ITCZ)
Rain fall converges around this line
Line shifts during el nina/la nino
Extratropical Cells
Outside of tropical area
Temperate storms
Cyclone rotation
Rotates counterclockwise in the northern hemisphere
Cyclone formation
Air rises and deflects
-NH:right(counterclockwise) around low pressure
-SH:left(clockwise) around high pressure
Tropical Cyclones
Tropical storms, hurricanes(typhoon)
26 degrees Celsius minimum to form
Counter-clockwise rotation in NH (opposite in SH)
Travels from east to west within the easterly wind belt
Earthquakes causing Tsunamis
Under-water earthquakes have higher magnitude than land
After an earthquake occurs it takes a long time for that area to have another earthquake
Earthquake must happen underwater in order to produce a tsunami
Effects of Earthquakes
Speeds up Earth’s rotation
Changes rotation axis
Causes of waves
Moon and Sun
Earthquakes, volcanoes, landslides and storms
Wind
Tsunami Waves
Circular motion of all molecules in a wave pushes it forward
Wave motion penetrates the water column to 1/2 the wavelength
Tsunami waves have wavelengths of 200km
Tsunami waves get very high at the shoreline
Evidence of Tsunami
Use soil and landscape to approximate wave height and tell where tsunamis happened
Why are satellites not always in geostationary orbits?
Launch costs are high because it needs a rocket
The signals are weaker because they are farther away from Earth
Rotate on gravitational pull
Majority of scientific satellites are Low Earth Orbiters because
They evolve around the Earth much quicker than geostationary
Need fuel to maintain orbit
Shorter life span
Passive Remote Sensing
Measure the reflected sunlight or thermal radiation
Detect sunlight radiation reflected from the earth
They do not emit their own radiation, but receive natural light
Satellite Geodesy
Science discipline to study the size, shape, and changes to planets
Active Remote Sensing
Emit artificial radiation to monitor the earth surface or atmospheric features
They do not depend on daylight and are hardly affected by clouds, dust, fog, wind and bad weather conditions.
Triangulation & Satellites
Need 3 different satellites in order for a GPS to know where you are
Altimeter
measures the time taken by a radar pulse to travel from the satellite antenna to the surface and back to the satellite receiver. Combined with precise satellite location data, altimetry measurements yield sea-surface heights
Bathymetry
Variation in depth of ocean floor
Salinity of water
Reflects the balance between the addition of freshwater and evaporation
Depends of temperature (warm water can hold more salt)
Salinity of ocean changes with depth
Causes of Ocean Circulation
Earth rotation/Coriolis effect
Surface currents– wind, uppermost 10% of ocean
Gravity
Solar heating and salinity
Continents and seafloor topography
Gyres
Large circular flow patterns
Clockwise in Norther seas and counterclockwise in southern
Direction of water movement is
Approximately 90 degrees to the right of the wind in the North
Ekman transport
Interaction of current velocity with Earth rotation
Causes water column to spiral
Geostrophic gyres
Water pressure equilibrium in an area so it rotates into a gyre
Deep water circulation
Brings heat from the equator to areas above and below the equator
Upwelling and downwelling driven by density
Downwelling
Wind drags water along surface
Develops near coast
Oversupply of water develops along shore and must sink
Warm, nutrient poor
Upwelling
Water moves away from coast so there is a shortage of water at coast so water moves upwards
cold, nutrient rich
Equatorial Upwelling
Deflects right in N and left of wind in S because of Coriolis effect
Upwelling causes the surface of the equator to be cooler and nutrient rich
Deep water formation
Thermohaline Circulation: cold, salty water sinks
Forms at high latitudes because of ice and temperature
Deep water circulation can be very slow
River/stream formation
Created as water is added to the surface
2 sources that generate stream flows
Gravity: pulls water down
Friction: resists water flow (river bottom, side of river)

These two forces work against each other

Stream formation
Erosion of soil
Downcutting in channels

Softer the material, the easier this is

Dendritic drainage networks
Branching, or treelike network of drainage
Radial drainage networks
Typically centered on a point of uplift
More downhill gradient, water ail move more quickly and carve paths
Types of drainage basins
Exorheic: basins that drain to the ocean

Endorheic: basins that drain to inland lakes: water never reaches the ocean

Stream velocity
Skinnier, and deeper: less friction

Wide, and shallow: more friction

Velocity slows with friction
Velocity increases farther from the banks
Wetted perimeter: length of bank in contact with stream

Erosion
Rivers carry both solid particles and dissolved sediments
Sediment transport
High velocity= larger grain transport
As river velocities decrease, larger grains drop out on the bed
Longitudinal profile
As you move downstream: slope decreases, cross sectional shape becomes wider and shallower (sediment at the end makes it shallower, and friction makes it expand wider)
Meander evolution
After meander develops (because of soft material being eroded) erosion increases and creates a cut bank on outer bank

Increases meander and makes it more sinous

Cutoff occurs and creates an ox bow lake– river becomes less sinous

Drainage Evolution
1. Uplift happens (mountain building)
2. Water starts flowing down
3. Erosion creates meandering
4. Erosion creates flatter land and fertile soil

Streamflows are a major agent of change

Stream Piracy
One stream captures flow from another

Results from headward erosion and built up sediment
Results in a dry channel

Floods
Too much water
Make massive changes to the landscape quickly
Deposit and erode dramatic amounts of sediment
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