Exam 3 Study Guide

Flashcards based on lecture notes for Exam 3 Review.

Why does the Earth have seasons?

Because Earth is tilted on its axis (23.5°), different parts receive varying amounts of sunlight throughout the year as Earth orbits the sun.

What is the general pattern of solar heating on Earth, and how does it vary by latitude?

The equator receives the most direct sunlight and energy, while the poles receive the least. Heating decreases from the equator to the poles.

What are the main aspects of the Coriolis effect?

Due to Earth’s rotation, moving air and water are deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. The effect is stronger at the poles and zero at the equator.

How do large-scale wind patterns influence surface ocean circulation?

Trade winds and westerlies drive surface currents, transferring energy to the ocean and creating large-scale gyres and currents like the Gulf Stream.

What is a gyre, and what factors influence circulation in the North Atlantic?

A gyre is a large system of rotating ocean currents. The North Atlantic gyre is driven by wind patterns, the Coriolis effect, and continental boundaries, featuring currents like the Gulf Stream and Canary Current.

What are some similarities and differences between gyres in the northern and southern hemispheres?

Similarities: Large, circular current systems driven by wind and Coriolis. Differences: Gyres rotate clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere due to the Coriolis effect.

Which latitudes are typically wet/cloudy, and which are arid/desert regions?

Wet/cloudy: Equator (0°) and around 60° N/S (low-pressure zones). Dry/deserts: Approximately 30° N/S (high-pressure zones).

Why do winds come from the east between 30° S and 30° N?

Trade winds blow from subtropical highs toward the equator. They are deflected west by the Coriolis effect, becoming easterlies.

Describe Ekman transport and its effect on vertical circulation.

Surface winds combined with the Coriolis effect result in a net water movement 90° from the wind direction. This leads to upwelling, where water moves away from the coast, and downwelling, where water moves toward the coast.

What drives thermohaline circulation, and how does it work?

Thermohaline circulation is a global conveyor belt driven by temperature and salinity differences. Cold, salty water is dense and sinks in polar regions, forming deep water.

How do temperature, salinity, and density vary with depth in the ocean at different latitudes?

Tropics: Strong thermocline, halocline, and pycnocline. Mid-latitudes: Moderate stratification. Poles: Cold surface resulting in weak or no stratification with uniform temperature and salinity.

Describe ocean density stratification.

The ocean is stratified into layers based on density, which is influenced by temperature and salinity. Warm, less salty water is less dense and found at the top, while cold, salty water is dense and sinks to the bottom.

Define thermocline, halocline, and pycnocline.

Thermocline: A zone of rapid temperature change with depth. Halocline: A zone of rapid salinity change. Pycnocline: A zone of rapid density change due to temperature and salinity variations.

What is ENSO, and what are its phases?

ENSO (El Niño Southern Oscillation) is a cyclic climate pattern in the Pacific. El Niño is characterized by weak trade winds and warm eastern Pacific waters, whereas La Niña features strong trade winds and cold eastern Pacific waters. ENSO impacts global weather patterns.

What is a wave?

A wave is energy moving through water. Particles move in circular orbits.

Define wave period, wavelength, and celerity.

Wave period: The time between crests. Wavelength: The distance between crests. Celerity: Wave speed, calculated as wavelength divided by period.

What are the differences between deepwater and shallow water waves?

Deepwater waves: Orbits do not touch the bottom. Shallow water waves: Orbits flatten, and the wave slows and steepens.

What controls wave size and speed, and when do waves break?

Wave size is influenced by wind speed, duration, and fetch. Wave speed depends on wavelength and depth. Waves break when the height exceeds 1/7 of the wavelength or when the depth is less than 1.3 times the wave height.

Name the different types of waves.

Wind waves, tsunamis and tides.

What factors control wind wave size?

Wind speed, duration, and fetch (distance wind blows).

Describe tides and tidal bulges and their causes.

Tides are caused by the Moon and Sun's gravity, and inertia. There are two bulges: one facing the Moon and one opposite due to inertia.

What are equilibrium and dynamic tide theories?

Equilibrium tide theory: idealized, uniform ocean, 2 tides/day. Dynamic tide theory: real ocean shapes, Earth’s rotation, Coriolis, etc.

Describe spring tides versus neap tides.

Spring tides: alignment of the Sun, Moon, and Earth, resulting in the highest tides. Neap tides: the Sun and Moon at 90°, resulting in the lowest range. Spring: full and new moon; Neap: 1st and 3rd quarter.

What are the major influences on tides?

Coriolis effect, continents which block tidal flow, and amphidromic systems.

Define amphidromic point.

Point around which tides rotate with no tidal range

Explain the three main types of tides.

Diurnal: 1 high, 1 low per day. Semidiurnal: 2 equal highs/lows. Mixed: 2 highs/lows of unequal size

What factors influence sediment supply and erosion?

Supply: rivers, cliff erosion, glaciers. Erosion: waves, currents, sea level rise, storms.

Describe longshore drift.

Waves hit the coast at an angle, moving sand down the coast in a zigzag pattern.

How do curvy or rough coastlines change over time?

Erode into straighter, smoother coastlines as wave energy is evenly distributed.

List some common coastal features.

Rocky: cliffs, headlands, sea stacks. Sandy: beaches, spits, barrier islands.

What causes ocean acidification, and what are its effects?

Caused by CO₂ dissolving into oceans. Forms carbonic acid, lowers pH. Harms organisms that form calcium carbonate (e.g., corals, shellfish).

What are the causes and evidence of global warming?

Cause: Greenhouse gases (especially CO₂ from fossil fuels). Evidence: rising temps, melting ice, sea level rise, earlier springs, species range shifts.

Which minerals crystalized out of seawater during the great oxidation event?

Limestone

CO2 is sequestered in what kind of rock?

Limestone

The abundance of nitrogen is because:

Volcanic ammonia transforming to N_2 under ultra-violet light

Why is Earth's temperature at the equator hotter?

The sun's rays hit the equator most directly because poles are hit on an angle and solar radiation passes through a thicker atmosphere at high latitudes

Why is Earth's axis tilted?

The planetesimal that made the moon hit it

What heat source drives mantle convection?

Decay of radioactive elements

Which way does the world turn?

Counter-clockwise

If an archer stands at the north pole and shoots an arrow directly aimed for the equator, what will the effects of Earth's rotation have?

The arrow will travel to the west

What is the velocity at the equator?

1667

Objects launched from the equator have how much more momentum as objects 45 degrees N latitude?

2x

Coriolis effect:

Winds north from the equator are deflected east, winds from the north pole are deflected west

What is the boundary between the troposphere and stratosphere called?

Tropopause

What's Earth's tilted axis?

23.5 degrees

What is the boundary between the troposphere and stratosphere?

Tropopause

If Earth wasn't on an axis, what wouldn't it experience?

Seasons

The primary driver of thermal energy exchange between the ocean and atmosphere is:

Solar radiation

Coriolis deflections in the northern and southern hemispheres are:

Mirrors of each other

Convection belts:

Hadley, Ferrel, Polar

What modifies the pattern of surface winds and oceanic circulation currents?

Continental land masses

Wind moves from:

High pressure to low pressure, and rising air creates low-pressure surface

What kind of pressure is found at the polar and Ferrel cells?

Low pressure

Jet streams:

Low pressure, narrow air currents traveling west to east at the tropopause

What accounts for the desert belts at 30 degrees north and south latitude?

Air descending at the boundary between the Hadley and Ferrel cells has lost its moisture

Are high-pressure systems rainy or fair?

High pressure = fair, Low pressure = rainy

The winds of a nor'easter that clobbers Cape Cod originate from:

B Canada/Maine

Nor'easter systems travel:

West to east

The prevailing surface winds between the equator and 30 degrees latitude are:

Trade winds and move east to west

Trade winds are:

0 degrees to 30, east to west

Westerlies are:

30 degrees to 60, moving west to east

In a high-pressure cell with downdrafts, is the flow clockwise or counterclockwise?

Clockwise in the Northern Hemisphere

In the northern hemisphere, anticyclones spin:

Clockwise and have dry, high-pressure centers

Oceanic circulation at the surface is controlled by:

Prevailing wind directions

Geostrophic gyres:

A flow of current around the periphery of an ocean basin; there are 5 ocean-scale gyres

Advection:

The transfer of heat or matter horizontally by fluid flow

Cold waters upwell off the coast of California due to Ekman transport. What direction is it going?

North to south

Wind from south to north blows along a coast to the east in the Northern Hemisphere. Will it lead to upwelling or downwelling?

Downwelling

Is the Gulf Stream upwelling or downwelling?

Upwelling

What about the Labrador Current?

Down