Heat Distribution and Atmospheric Dynamics Study Guide

Energy Source Limitation: If the sun were the only source of energy heating the air directly, the air would be extremely cold.
Sequence of Heating: Heat transfer mechanisms occur after the land and water on Earth absorb solar energy.
Primary Mechanisms:
- Conduction: This occurs when energetic molecules from the land and water collide with molecules in the air. This physical contact transfers energy from the Earth's surface directly to the air.
- Convection: Heat is distributed as air circulates. Warm air, which is less dense, rises upward. Cooler air, which is more dense, descends to take the place of the rising warm air close to the ground.
- Radiation:
  - The ground absorbs medium-wavelength solar radiation, which heats the surface.
  - Earth then emits long-wave infrared radiation.
  - Greenhouse gases, specifically water vapor ( $H_2O$ ) and Carbon Dioxide ( $CO_2$ ), absorb these longer wavelengths (infrared radiation) emitted by Earth, trapping heat in the atmosphere.

Cause of Imbalance: Global heat imbalance is primarily caused by the tilt of the Earth on its axis and the curvature of the Earth's surface.
Consequences: This heat imbalance is the fundamental driver responsible for weather patterns and global climate.
Redistribution Methods: Heat is redistributed across the Earth's surface by two main systems:
- Ocean currents.
- Air currents (wind).

Absorption Capacity: Water is highly efficient at capturing energy, absorbing up to $90\%$ of the solar energy that hits it.
Surface Coverage: Over $70\%$ of the planet's surface is covered by oceans.
Depth Distribution: Energy absorbed by the water at the surface is distributed throughout the depth of the ocean.
Mixing Mechanisms: Once the surface water is heated, it undergoes mixing through:
- Waves.
- Turbulence.
- Ocean currents.
The Gulf Stream and North Atlantic Drift:
- The Gulf Stream is a warm current originating in the Caribbean.
- It carries warm water across the Atlantic to the coasts of Canada and Great Britain.
- The warm water heats the surrounding air, which often results in the formation of dense fog.

Major Currents and Drifts:
- Pacific Ocean: Oyashio current, Kuroshio current, North Pacific current, Alaska current, California current, North Equatorial current, Equatorial Counter current, South Equatorial current, East Australia current, and Peru current.
- Atlantic Ocean: Labrador current, Gulf Stream, West Greenland current, East Greenland current, North Atlantic Drift, Canary current, N. Equatorial current, Equatorial Counter current, S. Equatorial current, Guinea current, Brazil current, Benguela current, and Falkland current.
- Indian Ocean: S. Equatorial current, West Australia current, and Aguilhas current.
- Global/Southern Ocean: West Wind Drift.

Thermal Energy Transfer: The atmosphere transfers thermal energy mainly through global wind patterns.
Wind Types:
- Prevailing Westerlies: Winds that originate from the West and flow toward the East.
- Prevailing Easterlies: Winds that originate from the East and flow toward the West.
The Coriolis Effect:
- The Earth is constantly rotating on its axis, and the atmosphere rotates with it at the same speed.
- Moving objects or convection currents on the Earth's surface tend to veer sideways from their intended original course due to this rotation.
Jet Streams:
- These are currents of extremely fast-moving air located approximately $10$ \text{ to } $15\,km$ above the Earth's surface.
- They flow from West to East.
- They have a significant influence on precipitation levels and the development of thunderstorms.
- Pilots utilize jet streams to increase the speed of flights and reduce travel time.

El Niño ("Little Boy"):
- Frequency: Occurs every $3$ \text{ to } $7$ years.
- Mechanism: The wind direction over the South Pacific reverses, causing the wind to flow East instead of West.
- Temperature Impact: This reversal develops above-average sea-surface temperatures across the east-central equatorial Pacific.
- Weather Effects: Causes heavy rains on the west coast of South America and leads to droughts in Southeast Asia.
La Niña ("Little Girl"):
- Mechanism: Characterized by the periodic cooling of sea-surface temperatures across the east-central equatorial Pacific.
- Process: Strength of westward winds increases. Cool water from the deep ocean near the west coast of South America rises (upwelling), warms slightly, and flows West across the Pacific toward Southeast Asia and Australia.
- Weather Effects: Produces conditions that are significantly wetter than normal.

Orographic Precipitation:
- Occurs when warm, moist air is forced to rise against a mountain range.
- As the air rises, it cools and condenses, falling as precipitation (rain or snow) on the windward side.
- Rain Shadow: This is the region on the leeward side of the mountain (the side sheltered from the wind) that receives very little rain.
- Example: In Western Canada, moist air from the Ocean hits Vancouver, rises over the mountains, and descends as warm, dry air toward Calgary. This rapid descent of air is known as a Chinook, an Aboriginal word meaning "snow eater."
Coastal Breezes:
- Sea Breeze (Daytime):
  - The sun warms both land and water, but land warms faster due to the high specific heat capacity of water.
  - Warm air rises off the land, and the cooler air over the water moves in to replace it, creating a breeze from the sea to the land.
- Land Breeze (Nighttime):
  - At night, water cools more slowly than land, meaning the air over the water is warmer than the air over the land.
  - Warm air rises off the sea, and the air moves from the land toward the sea. This is the reverse of a sea breeze.

Climate and Soil: Characterized by a mild climate and rich, nutrient-dense soil.
Seasonal Variation: Features $4$ distinct seasons.
Temperature Range: Temperatures vary significantly, ranging from below freezing in the winter to $30^\circ C$ in the summer.
Water Availability: Droughts in this biome are uncommon.
Typical Fauna: Includes deer, foxes, squirrels, mice, snakes, birds, and an abundance of insects.