Earth Systems and Atmospheric Science: Structured Study Notes

Earth's Spheres and System Theory

Overview of Earth's Four Spheres

The Earth is composed of four major spheres that interact to regulate the planet's environment and processes. These spheres are:

• Atmosphere – The layer of gases surrounding Earth.

• Hydrosphere – All water bodies, including oceans, lakes, and rivers.

• Biosphere – All living organisms.

• Lithosphere (Geosphere) – The solid, rocky part of Earth.

Both abiotic (non-living) and biotic (living) components interact, with matter and energy flowing through each sphere.

Definition of a System

• System: An ordered, interrelated set of things and their attributes, linked by flows of energy and matter.

• Systems have inputs, outputs, and storage components.

System Theory

• Flow of energy and matter links system components.

• Energy can be transformed from one state to another.

• Inputs and outputs are stored and retrieved.

Open vs. Closed Systems

• Open systems: Exchange inputs and outputs with surroundings.

• Closed systems: Self-contained, no exchange with surroundings (rare in nature).

System Feedback

• Feedback pathways allow outputs to influence future inputs.

• Negative feedback: Stabilizes system, resists change.

• Positive feedback: Amplifies change, can lead to system instability.

System Equilibrium

• Balance occurs when inputs and outputs are equal over time.

• Dynamic equilibrium: System fluctuates but remains stable overall.

• Threshold: Crossing a threshold can abruptly shift the system to a new state.

Earth in the Solar System

Planetary Atmospheres

Planet	CO2 Concentration	Notes
Venus	96.5%	Very dense atmosphere
Earth	0.04%	Thin atmosphere
Mars	95%	Less dense than Venus

Mercury has a very dense core due to gravity. Magnetic fields are strong on Earth, weaker on Mars.

Stellar Environment and Earth's Orbit

• All solar energy comes from the sun; cosmic rays impact Earth.

• Earth's axial tilt: 23.5° (varies between 22.1° and 24.5° over 40,000 years).

Solstice vs. Equinox

• Solstice: Greatest difference in day length.

• Equinox: Day and night are approximately equal.

Earth's Orbit and Moon Phases

Moon Phases

• Tides follow the moon.

• 28-day orbit.

• Sun lights the moon; always opposite phases.

• Half the moon is always lit.

• New moon not seen because it is fully lit by the sun.

Solar Radiation and Electromagnetic Spectrum

Electromagnetic Spectrum

All wave lengths of electromagnetic energy are emitted by the sun and interact with Earth's atmosphere.

• High energy (short wavelength): Gamma rays, X-rays, UV

• Low energy (long wavelength): Infrared, radio waves

Solar Radiation Spectrum

• Emitted wavelength: 0.2 to 0.4 μm

• Blackbody absorbs radiation

• Atmospheric gases absorb various wavelengths

Main Parts of Solar Radiation

1. Gamma rays, X-rays, UV (8%)

2. Visible light (47%)

3. Infrared (45%)

Solar Insolation and Irradiance

• Solar insolation: Solar radiation reaching a horizontal plane at Earth.

• Tropics receive 2.5x more solar energy than poles due to Earth's curvature.

Longwave Radiation and Albedo

Longwave Radiation

• Creates greenhouse effect (average 32°C).

• Water vapor is a major contributor (about 80% of the effect).

Albedo

• Reflectance of Earth's surface.

• White surfaces reflect more sunlight, reducing heat absorption.

Solar Radiation Balance

• Average daily net radiation = incoming shortwave radiation – outgoing longwave radiation.

Earth's Atmosphere: Structure and Evolution

Atmospheric Layers

Layer	Altitude	Key Features
Troposphere	Surface to 18 km	90% of atmosphere, greenhouse effect
Stratosphere	18 km to 50 km	Ozone layer location
Mesosphere	50 km to 80 km	Temperature decreases with altitude
Thermosphere	80 km upward	Temperature increases at 480 km

Atmospheric Temperature Profile

• Higher altitude = less dense gases.

• More heat is absorbed at higher altitudes due to ozone layer.

Ozone Layer and UV Radiation

• Ozone absorbs UV radiation, protecting life on Earth.

• UVA: Least harmful; UVB: Skin cancer risk; UVC: Most dangerous, absorbed by ozone.

Ozone process:

• Atomic O

• O2 → O + O

• O3 → O2 + O

• Ozone is formed, destroyed, and reformed in a cycle.

Pollution and Atmospheric Distribution

Types of Pollution

• Particles: Generated by combustion/wind storms (e.g., human hair).

• Aerosols: Fine solid or liquid particles suspended in gas (e.g., spray paint).

• Gases: Chemical vapors (e.g., CO2, CH4).

Distribution

• Winds and temperature inversions affect pollution spread.

• Warm air layers can trap pollution in the atmosphere.

Energy Balance and Heat Transfer

Energy Balance

• Maintains Earth's temperature within habitable limits.

• Air density: 1.2 kg/m3

• Water density: 1000 kg/m3

Atmospheric Escape Window

• Longwave radiation escapes between 8 and 13 μm.

• Escape window is shrinking, trapping more heat and contributing to climate change.

Heat Transfer Processes

• Sensible heat: Heat you can feel and measure.

• Latent heat: Heat absorbed or released during phase changes (e.g., water evaporation).

• Specific heat capacity: Amount of energy required to raise temperature by 1°C.

For water: $4184 \text{J/kg/K}$; for vaporization: $540 \text{cal/g}$

Solar Radiation and Energy Transfer

Shortwave and Longwave Radiation

• Shortwave: Reflection, scattering, absorption.

• Longwave: Emission from Earth's surface.

Net Radiation Equation

Net radiation is the balance between incoming and outgoing radiation:

• $\text{SW}_{\text{down}}$ = downward shortwave radiation

• $\text{SW}_{\text{up}}$ = upward reflected shortwave radiation

• $\text{LW}_{\text{down}}$ = downward longwave radiation

• $\text{LW}_{\text{up}}$ = upward longwave radiation

Net radiation formula:

$\text{Net Radiation} = \text{SW}_{\text{down}} - \text{SW}_{\text{up}} + \text{LW}_{\text{down}} - \text{LW}_{\text{up}}$

Temperature Variation and Climate Controls

Main Controls of Temperature Variation

• Latitude

• Elevation

• Cloud cover

• Land-water heat capacity

Coastal vs. Continental Climate

Coastal	Continental
Takes more energy to heat up (high specific heat)	Heats up and cools down faster (low specific heat)
Temperature distributed, evaporation occurs	No mixing materials, temperature fluctuates

Wind Chill and Humidity Index

• Wind chill: Measures rate of heat loss from skin due to wind.

• Humidex: Indicates discomfort due to humidity; higher values mean more discomfort.

Atmospheric Circulation and Pressure Zones

Global Circulation Patterns

• General global circulation: Movement of air masses around the planet.

• Secondary circulation: Migratory high and low pressure systems.

• Tertiary circulation: Local winds and water patterns.

• Meridional flows: North-south movement along meridians.

• Zonal flows: East-west movement along latitudes.

Pressure Zones and Wind Development

• Warm, humid air = low pressure

• Cold, dry air = high pressure

• Wind direction is determined by pressure gradients.

Coriolis Effect

• Pressure gradient force + Coriolis force = geostrophic wind (high in troposphere).

Four Broad Pressure Zones

1. Equatorial low pressure (heavy rainfall, trade winds)

2. Subtropical high pressure (dry, hot, strong in summer)

3. Subpolar low pressure (rain and snow, strong in winter)

4. Polar high pressure (cold and dry)

Hadley Cells and Jet Streams

• Hadley cells: Circulation cells idealized over Earth's surface.

• Jet streams: Fast, concentrated bands of westerly wind.

• Rossby waves: Undulating jet streams that influence weather patterns.

Additional info: These notes are based on Earth system science and atmospheric science, not organic chemistry. They cover planetary atmospheres, solar radiation, energy balance, and climate controls, which are foundational for environmental science and meteorology.