Lab Practical 1 - Ocean 100

What is Latitude?

One’s north-south position

Are lines of latitude horizontal or vertical?

Horizontal

What does latitude define the geographic poles?

90 degrees N and 90 degrees S

At what latitude is the equator found?

0 degrees

How much does each line of latitude degree increase by?

15 degrees

What does it mean that latitude lines are “parallels”?

They are parallel to each other and equally spaced

How does the distance between two latitude lines change as latitude increases?

It stays the same distance (all lines equidistant)

How does the circumference change as latitude increases?

It progressively decreases

What is longitude?

Defines one’s east-west position

Are lines of longitude horizontal or vertical?

Vertical

What is the range of longitude degrees?

0 degrees E/W to 180 degrees E/W

What compass direction is negative degrees for longitude?

West

What does each line of longitude increase by?

15 degrees

What is the line of longitude that is 0 degrees E/W called?

Prime Meridian

What is the longitude line at 180 degrees E/W called?

International Date Line

What are longitude lines also known as?

Meridians

Why are longitude lines also called meridians?

Local noon occurs simultaneously from pole to pole along a given longitude line

How does circumference of longitude lines change as longitude changes?

Circumference remains the same at each longitude line

How does the distance of longitude lines changes as the line reaches the poles?

The distance decreases

How many arc minutes is 1 degree?

60 arc minutes

How many arc seconds is 1 arc munute?

60 arc seconds

What is the format of latitude-longitude coordinates?

degree minute second (N/S) degree minute second (E/W)

What is the symbol for arc minutes?

‘ (ex. 60’)

What is the symbol for arc seconds?

‘‘ (ex. 60’’)

How to convert a degree minute second format to degrees?

1. Convert minutes to degrees by multiplying by 1 degree/60’ (results in degree decimal)

2. Convert seconds to degrees by multiplying by 1 degree/3600’’ (results in degree decimal(

3. Add stated degree with converted minutes and seconds

What is a great circle?

Circle will be the largest possible, cuts sphere in half perfectly

Where are great circles?

All longitude lines and equator

What is a small circle?

When the plane does not intersect the center of the sphere

Where are small circles?

At all latitude lines except for the equator

What is a nautical mile?

One “arc minute” of distance in latitude along a great circle at sea level

How many nautical miles is one arc minute?

1 nautical mile

How many nautical miles in one degree latitude?

60 nm

Is the nautical miles for longitudinal measurements the same all throughout Earth?

No, the equator is a great circle so 1 arc minute equals 1 nautical mile. But, distance is nautical miles between longitudinal lines decreases as the lines converge to a single point at each pole.

How much does the Earth rotate per hour?

15 degrees E per hour

When people along the Prime Meridian are experiencing local noon what are people along the International Date Line experiencing?

Local midnight

What is UTC?

Universal Coordinated Time where it expresses current time at the Prime Meridian

What is the format of UTC?

24 hour XXXX format

example- 4:00 pm = 1600 UTC

What is the relationship between UTC and East?

One hour is added for every 15 deg longitude to the east

What is the relationship between UTC and West?

One hour is subtracted from UTC for every 15 degrees longitude to the west

How to find UTC time from a longitude degree?

1. Multiply the degree by 1 hour/ 15 deg to find time zone

2. Round to last complete time zone

3. Figure out if you need to subtract (west) or add time zone (east) to UTC time

How to find the east-west distance in arc minutes from two locations? (4 steps)

1. Add the degrees longitude together

2. Convert degrees to minutes

3. add the minutes of the original location

4. add those minutes to the converted minutes

How to find the east-west distance in nautical miles from two locations? (3 steps)

1. Find arc minutes (previous question)

2. Use the latitude to find the conversion factor from the table

3. Use conversion factor to convert from arc minutes to nautical miles

How to find the distances in latitudes?

Simply use conversion factors (since all lines of latitude are equidistant at all points of longitude)

What do you need to do every time you are converting something with nautical miles and longitude?

Refer to latitude and the conversion table for longitude depending on the latitude

In a mercator projection how is spacing between lower latitudes? How are the continents?

Spacing in lower latitudes are stretched less (N/S) and the continents are less exaggerated

In a mercator projection how is spacing between higher latitudes? How are the continents?

Spacing between higher latitudes are stretched more (N/S). Continents are more exaggerated.

In a mercator projection how is spacing between longitudes closer to the equator? How are the continents?

The spacing is not stretched (E/W). Continents are not exaggerated.

In a mercator projection how is spacing between longitudes farther from the equator? How are the continents?

Spacing between longitudes farther from the equator are stretched (E/W). Continents are more exaggerated.

What process is responsible for bathymetric features?

Plate tectonic processes

What observations of continents did Alfred Wegener make (2)?

The continents fit together like a jigsaw-puzzle

Similar rock types and fossils on coastlines

What hypothesis did Alfred Wegener make?

Continental drift

What is the hypothesis of continental drift?

The continents were once a single “super-continent” but they have slowly drifted through oceanic crust to their current positions

What is the basic hypothesis of sea-floor spreading?

As oceanic crust spread apart, molten material rose from the Earth’s interior to form new oceanic crust along oceanic ridges

What is a hypothesis?

A proposed scientific explanation for a set of observations

What are three features of a hypothesis?

• Can be tested, but can’t be proven (testable idea)

• can be potentially false

• can lead to theory when combined with other hypotheses

What is a theory?

Well-tested explanation that unifies a broad range of observations. Scientifically tested and proven

What two things can Earth’s interior be subdivided based on?

Composition or behavior

How thick is the lithosphere?

100 km thick

What compositions is the lithosphere made of? What types of crusts, etc.?

Continental crust, oceanic crust, uppermost solid portion of mantle

What layer of Earth do tectonic plates move on?

Asthenosphere

What is the behavior of the asthenosphere?

Partially melted layer (plastic)

The mantle changes in its behavior with ____

changes with depth, temperature, and pressure

What are the two parts of the Earth’s core?

Liquid outer core and rigid inner core

How can rigid plates move relative to one another?

New lithosphere is added along some plate margins and old lithosphere is removed from the surface along other plate margins

What is a transform boundary?

Occurs where two plates slide past each other horizontally

What is a divergent boundary?

Where two plates move away from each other

What do divergent oceanic-oceanic boundaries create?

Ridges

What do divergent continental-continental boundaries create?

Rifts

What are the two types of transform boundaries?

fracture zones and transform faults

What is a convergent boundary?

Where two plates move towards each other

What are the two types of convergent boundary location types?

Subduction zones and continental collisions

What 4 things drive plate motion?

1. Asthenospheric push

2. lithospheric slide

3. lithospheric pull

4. lithospheric suction

What is asthenospheric push?

Buoyancy driven rising of magma push plates apart

What is lithospheric slide?

Gravity-driven, plates slide down elevated flanks

What is lithospheric pull?

Gravity-driven, plates pulled down when more vertical

What is lithospheric suction?

Traction-driven, convection currents

What are earthquakes?

The release of accumulating elastic strain within the lithosphere through essentially instantaneous motion along some fault surface

What is the focus?

Exact location of an earthquake

What is the epicenter?

Map location on the surface directly overlying the focus

What is the Richter magnitude?

the measure of ground shaking intensity caused by an earthquake

What type of earthquakes happen at divergent plate boundaries?

Relatively shallow

What types of earthquakes happen at convergent boundaries?

Relatively deep earthquakes

What type of earthquakes happen at transform boundaries?

Relatively shallow earthquakes

What type of volcanic activity occurs at divergent boundaries?

Typically undersea, less extreme and explosive

What type of volcanic activity occurs at convergent boundaries?

Undersea and on land; more extreme and explosive

What type of volcanic activity occurs at transform boundaries?

Absent

What are hot spots?

Where rising mantle plumes of asthenosphere melt through the overlying lithosphere and erupt as magma on the ocean floor and can build high up enough to form volcanic islands

What are two seamount patterns?

1. Seamounts farther from the active hot spots are older than seamounts closer to the hot spot

2. seamount chain orientation is directly related to the direction of plate motion

What has a faster spreading rate, the Atlantic or Pacific ocean?

The Pacific Ocean

What is the spreading rate?

Distance (cm) / oldest crust age yr

What is Archimedes’ Principle?

A floating object displaces a volume of fluid equal to the mass of the object

Density equation

density = mass/volume

Mass equation

Volume x Density

Volume Equation

L x W x H

Gravitational force and Archimedes’ Principle

Pulls downward and displaces water in all directions

Buoyancy force and Archimedes’ Principle

Net result of hydrostatic pressure pushing upward

State of equilibrium

Gravitational force and buoyant force are equal. Stable state in vertical position

If Mass increases, then density ____?

Increases

If density increases, then mass ___?

Increases

What are the two units of density?

g/cm³

kg/m³