Mid term 2 Flashcards
Whats Air pressure
Weight of the atmosphere(Motion, size, and number of molecules in the air) Heating of the air lowers the pressure of the air
What does Pressure Do ?
ITS responsible for the initial movement of air and The closer spacing of isobars, the higher pressure gradiant= the stronger wind
Whats the Coriolis effect
Since the earth rotates The wind/ Air masses deflect to the right in the northern hemisphere, deflect to the left in the southern hemisphere, No deflection at the equator and max deflection at the poles.
What occurs at a Low pressure system
Cyclones form at the centre of low atmospheric pressure.
- Air spirals inward and upward
-Associated with cloudy and rainy weather
- makes warm moist air
what happens at high pressure systems
Anti cyclone: center of high atmospheric pressure
- Air spirals downward and outward
- Fair weather
- makes cold, dry air masses
Hadley cells
- The closest cell to the equator
- Warm surface=low pressure
- Lighter(less dense) ascending air
- Converging air holding a lot of moisture
Ferrel Cells
- Between 30-60 degrees latitude
-Air sinks at 30 and moves towards the poles - ## Produces the “westerlies” at the surface (because of coreilos
Polar cells
- cold and dry air
-Air descends as it reaches the poles because it becomes colder and denser
-Variable wind direction because of weak heating =polar easterlies
Jet streams(polar)
- Due to Ferrel and polar cells and the Coriolis force converging
-winds of different temperatures and densities meet
-stronger when there are larger differences
-weak in summer strong in winter
Jet stream(subtropical)
Air from equator is warm and moist
-Air from poles is cold and dry = subtropical jet stream s
-where the Hadley and Ferrel cells meet
- weaker than the polar jet stream
Isobars
Lines on a map drawn through all points having the same atmospheric pressure
Global Circulation
Since the earth is rotating the equator receives more heat then the poles
Whats the order of the cells
Hadley at the Equator passes through the Subtropical jet stream, then into the Ferrel cell, then passes through the polar jet stream into Polar cells and at the very top, it’s the polar vortex
General Atmospheric Circulation Summary
- Polar circulation(60 degrees-> 90 degrees): polar front and polar jet stream cold air moves south
- latitude circulation(30-60 degrees): westerlies, subtropical high, sub-tropical jet stream
- tropical circulation(0-30degrees):
Trade winds, equatorial, Hadley cells - jet streams: polar and subtropical jet separate circulation zones
Thermocline
- The transition between warmer, well-mixed surface water and cold, stratified deep water.
- Epipelagic zone: region with enough sunlight for algae to use photosynthesis
Primary ocean forces
- solar heating
- winds
- coriolis
- gravity
solar heating
Heating causes water expansion
- 8 cm higher at equator than at mid-latitudes
- creates a slope water flows down the slope
Winds +gravity+Coriolis
- water will pile up in the direction the wind is blowing
- creates a a mound with slope- gravity tries to pull downhill
- but Coriolis acts against this and causes deflection to the right in the North hemosphere and left the south hemisphere
- This creates mounds in the ocean that water circulates: gyres
Gyres
- these are large circular currents in all major ocean basins
- there are 5 primary gyres in our oceans and one in the artic
what are the level of clouds
low clouds: nimbostratus, stratus, stratocumulos
middle clouds: lenticular, altocumulus, altostratus
High clouds: cirrocumulus, Cirrostratus, cirrus, anvil head clouds
Cloud formation process
- adiabatic cooling by vertical lift
- Air parcel cools to the dew point temperature
- Air parcel becomes saturated
- Condensation occurs
Lifting condensation
The point in the atmosphere where it becomes saturated (i.e. bottom level of clouds
Clouds with vertical development
Cumalos, Cumulonnimbus
Convergent lifting
- air flows toward an area of low-pressure
- low pressure center, air converging and ascending, cooling condensation occuring
Convectional lifting
- warmer surfaces produce conventional lifting due to local heating
- The air above the warmer surfaces is heated and rises
- Examples include water to land, urban heat islands, ploughed field
Orographic lifting
Orographic lifting occurs when air is forced to ascend upslope as it is pushed against a mountain
Frontal lifting
A front is the transition zone between two air masses of different densities
Usually separate air masses with contrasting temperatures
cold front
-The leading edge of advancing cold air masses is a cold front
- cold air forces warm air aloft
-400km wide
- precipitation behind the cold front
Warm front
- The leading edge of an advancing warm air mass is a warm front
- warm air moves up and over cold air
- Precipitation ahead of the warm front
- 1000km
Occluded front
- when a cold front overtakes a warm front
- dense cold air moves faster than the warm front
- usually form in low pressure regions
Life cycle of a midlatitude cyclone
- Cyclogenesis
- Open stage
- occluded stage
4.dissolving stage
Cycle takes 3-10 days
ENSO( El Nino Southern Oscillation)
Occurs when
- Higher pressure than normal over western pacific
-Lower pressure over eastern pacific
- trade winds(normally east to west) weaken
- shift in air pressure and winds= Southern oscillation
Impacts of ENSO
- Upwelling blocked in the eastern Pacific
- Fewer Nutrients
- Decrease in plankton
- can occur every 2-12 years (normally 3-5)
Cyclogenesis
- The development of strengthening of low-pressure region
- begins with boundary of cold polar air to the north and moist warm air to south
- a disturbance allows warm air to converge on the boundary and begin to rise over the cold front, setting up counter- clockwise circulation
Open stage
- Counter-clockwise flow draws warm, moist air into the low-pressure center
- cold air moves to replace the warm air
- convergence causes air to rise(no-where else to go)
occluded stage
- faster moving cold front wedges beneath the slow warm front
- forms an occluded front which pushes warm air up causing precipitation
dissolving stage
-The cold air mass cuts off the warm air mass from its source of energy and moisture
- warm air trapped above cold air weakens the low-pressure system
- the cyclone then dissolves
principles of superposition
Rocks and sediments are always arranged with the youngest bed toward the top of the rock formation and the oldest at the base(only if undisturbed)
Physical structure of a hurricane
- The central area of a hurricane is called the eye, which is quiet and warm(air sinks rather than rises and prevents cloud formation)
- around the eye swirls a thunderstorm cloud called the eyewall, which is the area of most intense precipitation
Tornados
-visible condensation funnel from the bottom of the storm cloud
usually
-80m across
-wind speed 180km/h
-travel a few km before disappearing
Extreme
-3km diamater
-wind speed greater than 480km/h
-Travel 100km
storm surges
- coastal flood
- low-pressure region pulls up water into a dome beneath the storm
- water level falls in surrounding areas of high-pressure
- high wind speeds drive water build-up
- low lying areas are very vulnerable
- Hurricane Katrina caused an 8 m storm surge and Ian caused a 4m
Endogenic system
Internal processes that produce flows of heat and material from deep below the earths crust
Earth’s Mantle
-Average depth is about 2900km
-Two parts, upper and lower mantle
-consists 80% of earths volume
-Rocks in lower mantle are hot enough to deform and flow slowly
-Moho is the name for the boundary between uppermost mantle and the crust above
Minerals and rocks
Mineral: natural solid compound
with a unique chemical structure
and a crystalline structure
Rock: Assemblage of minerals
that can be divided into
categories:
* Igneous
* Metamorphic
* Sedimentary
Exogenic systems
- external processes that set into motion that erode by( Air, water, and ice)
- all of these are summed into the term “denudation” or “Strip off”
Divergent Boundaries
- plates move apart
- magma upwells and forms a new crust
- most at mid-ocean ridges (Iceland)
- a few within continents
(great rift valley of west Africa)
subduction
The edge of one plate descends
beneath another plate and dives into
the mantle
- Denser dives beneath lighter crust
(e.g. ocean below continental)
- This subducting plate then melts in the
mantle
- Occurs at the edge of the seafloor
spreading plates
- Where you find the deepest ocean
trenches
Transform Boundaries
Where plates slide past each
other
- Forms a fault
- Found between two segments of
mid-ocean ridge
- The motion produces
earthquake
ring of fire
Surrounds the Pacific
Basin
- Frequent volcano and
earthquake occurrence
due to subduction
- 90% of the world’s
earthquakes occur in
the Ring of Fire
