Final Exam Review for GGR214

Final Exam Information

The final exam for GGR214 is scheduled for April 24th from 9:00 to 11:00 AM in Gym A/B. The exam will last for two hours, and students are allowed to bring non-programmable calculators. Answers will be recorded on Scantron cards. It is important to bring a calculator for the numerical questions that will be included in the exam.

Exam Format

The exam will consist of various types of questions, totaling 68 marks:

Multiple Choice: 33 questions (33 marks)
Short Answer: 2 questions (10 marks)
Diagram/Drawing: 1 question (9 marks)
Numerical Answer: 2 questions (16 marks)

Students should note that equations and constants will be provided, and they should focus on those covered during the second half of the semester.

Coverage Breakdown

10% of the exam will be from lectures 1-5 (before mid-term):

Approximately 6 to 7 multiple-choice questions with no calculations required.

90% of the exam will be from lectures 6-10 (after mid-term), which will include topics such as:

Condensation
Winds
The Planetary Circulation
Air Masses and Fronts
Anthropogenic Climate Change

Review Strategy

The review session is not intended to teach the material again but to highlight key points. Students are responsible for understanding all content covered during the course, not just those discussed in the review.

Content Overview

Lectures 1 to 5 - Fundamentals

The structure of the atmosphere
The behavior of the atmosphere
The energy balance
The saturation concept

Condensation

Concepts:

Curvature effect and Solute effect
Cloud condensation nuclei (CCN)
Ice nuclei and their effects on clouds
Cloud formation mechanisms
Types of clouds that produce precipitation
Atmospheric stability

Curvature Effect

The curvature effect describes how smaller droplets have a higher curvature, increasing the relative humidity (RH) needed for equilibrium with the surroundings. For droplets with radii smaller than 1 μm, the RH needs to exceed 100% for equilibrium, inhibiting their growth and leading to rapid evaporation.

Cloud Condensation Nuclei (CCN)

Aerosols that act as cloud condensation nuclei must be wettable and large. Effective CCN sources include:

Over Oceans: Sea salt and dimethyl sulfide (DMS) from phytoplankton.
Over Continents: Emissions from combustion (e.g., wildfires) and volatile organic compounds from vegetation.

Solute Effect

The solute effect occurs when water vapor condenses on hygroscopic CCN, resulting in a solution that requires lower RH to remain in equilibrium; this promotes droplet growth below 100% RH.

Ice Nuclei

Ice nuclei facilitate ice crystal formation and are effective at lower temperatures, typically being less abundant than CCN. They include materials like clay minerals and organic compounds. Their effectiveness increases as temperatures decrease to below 0 °C.

Atmospheric Stability

Stability can be classified as:

Absolutely Stable: ELR < SALR < DALR
Absolutely Unstable: ELR > DALR > SALR
Conditionally Unstable: DALR > ELR > SALR

The stability of different air parcels impacts vertical motion in the atmosphere.

Cloud Formation Mechanisms

Clouds typically form through air cooling due to rising air. The five basic mechanisms include:

Convection
Orographic lift
Surface convergence
Frontal lifting
Divergence aloft

Winds

Winds can be classified into:

Geostrophic Winds
Gradient Winds
Surface Winds

Forces acting on air include:

Pressure Gradient Force (PGF)
Coriolis Force (CF)
Centripetal Force (CLF)
Friction

The Coriolis Force

In the Northern Hemisphere, the Coriolis force acts to deflect moving objects to the right and to the left in the Southern Hemisphere. Importantly, it does not cause deflections at the equator.

Coriolis Force Definitions

The Coriolis parameter (fc) relates to Earth's rotation and latitude:

f_{c} = 2 \\Omega sin \\phi with a value of 7.27 \\times 10^{-5} (radians) s^{-1}.

Geostrophic Wind Speed

Geostrophic wind speed (Vg) is inversely related to fc:

V_{g} = -\\frac{1}{\\rho} f_{c} \\\Delta P / \\\Delta x. Winds vary with pole proximity and are undefined at the equator.

Gradient Winds

Gradient winds occur when isobars are curved. These winds flow parallel to curved isobars while balancing PGF, CF, and CLF. Cyclonic winds blow counterclockwise around low-pressure systems, while anticyclonic winds blow clockwise around high-pressure systems.

Surface Winds

Surface winds experience friction, weakening the Coriolis force compared to the pressure gradient force, causing resultant winds to cross isobars at angles.

Weather Patterns

Low-pressure areas are associated with rising air and cloud formation.
High-pressure areas are linked to clear skies due to sinking air.

The Planetary Circulation

Planetary circulation governs pressure and wind patterns at the Earth's surface, dividing the globe into different circulation zones (Tropical, Extratropical, Polar).

El Niño – Southern Oscillation (ENSO)

ENSO involves a warming of ocean surfaces in the tropical Pacific and alters pressure patterns:

Normal (La Niña) Phase: High pressure in the central/eastern Pacific area.
El Niño Phase: High pressure reverses to low pressure, causing water to warm in the eastern Pacific.

Air Masses & Fronts

Air masses form in source regions with uniform surface properties. Their classification utilizes two-letter symbols indicating moisture (continental vs. maritime) and temperature (Arctic, Polar, Tropical). Four major air mass source regions exist:

High-latitude land/ice-covered oceans
Ice-free high-latitude oceans
Subtropical oceans
Subtropical deserts

Front Types

Different front types include:

Cold fronts (triangles)
Warm fronts (semicircles)
Stationary fronts (alternating triangles and semicircles)
Occluded fronts (purple lines with alternating semicircles and triangles)

Structural Characteristics of Fronts

Fronts are characterized by rapid temperature gradients within a zone extending approximately 100 km across and rising to at least 5 km in height. Weather associated with fronts includes cloud formation and precipitation.

Weather Implications of Fronts

Cold fronts promote sudden weather changes and heavy precipitation, primarily forming cumuliform clouds, while warm fronts produce widespread light precipitation from stratiform clouds.

Anthropogenic Climate Change

This topic covers observed changes in the Earth system, long-lived greenhouse gases, feedback effects, and future emission scenarios. It is vital to understand the difference between positive feedback (which amplifies changes) and negative feedback (which reduces changes).

Feedback Effects

The ice-albedo feedback illustrates how decreased albedo from melting ice leads to increased temperatures and further melting, creating a self-enhancing loop.

Shared Socioeconomic Pathways (SSPs)

These are scenarios predicting future development based on varying socioeconomic factors influencing greenhouse gas emissions, projecting different trends for 2100.

Exam Preparation Tips

Effective preparation entails studying 3-5 days before the exam, reviewing lecture slides, going through calculation examples, and practicing online quizzes. During the exam, it’s crucial to read questions carefully and manage time wisely.

GGR214 Final Exam Comprehensive Review

GGR214 Final Exam Comprehensive Review