Climate Dynamics and Milankovitch Cycles

Milankovitch Cycles

• Eccentricity cycle: 100,000 years; influences the length of seasons and seasonal solar radiation received.
• Axial tilt cycle: 41,000 years; affects the percentage of Earth's surface receiving direct sunlight.
• Precession cycle: 26,000 years; shifts the timing of seasons due to the rotation axis's wobble.

Solar Energy and Global Air Circulation

• Global air circulation regulates temperature and precipitation through uneven solar energy distribution.
• High latitudes lose more heat than they gain due to low angles of solar incidence and ice albedo.
• Low latitudes gain more heat, creating a balance that drives atmosphere and ocean circulation.

Rain Shadow Effect

• Windward side of mountains receives precipitation as rising air cools and condenses.
• Leeward side experiences dry conditions as descending air warms and retains moisture.

Sea Breeze Front

• Daytime: Land heats up faster; warm air rises, creating onshore breezes as cool ocean air moves in.
• Nighttime: Land cools faster; warm air over water rises, causing offshore breezes as cool land air replaces it.

Fronts and Storms

• Fronts are interfaces where differing air masses meet, leading to storm development.

Global Ocean Currents

• Wind-driven upper ocean currents and density-driven deep currents (thermocline circulation) interact.
• Currents are influenced by temperature and salinity, distributing heat and nutrients globally.

Global Ocean Conveyor Belt

• Series of thermohaline currents circulates water over roughly 1,000 years.
• Critical for moving large water volumes, regulating climate, and supporting aquatic ecosystems.

Sea Surface Temperature (SST) Measurement

• Average SST around 20°C; February 2024 recorded a peak at 21.06°C.
• Measured mainly via satellite detecting infrared radiation, supplemented by ship and buoy data.

ENSO – El Niño Southern Oscillation

• ENSO is a global ocean-atmosphere cycle affecting weather patterns, especially in the Pacific.
• El Niño occurs when east-central Pacific waters warm, altering currents and weather globally.
• La Niña involves cooler waters and stronger east winds; typically lasts longer than El Niño.
• ENSO events influence fisheries, agriculture, and are critical for predicting extreme weather occurrences.

Radiative Forcing

• Measures the energy imbalance as a result of altered energy inputs (e.g., greenhouse gases, aerosols).
• Important for quantifying climate change effects; expressed in watts per square meter (W/m²).

Climate Feedbacks

• Feedback mechanisms, like water vapor and cloud presence, directly impact climate stability.
• High altitude water vapor amplifies warming; clouds can reflect sunlight (cooling) or trap infrared radiation (warming).

Aerosols

• Small particles affecting climate through altering radiation absorption and reflection properties.

Exam Preparation Tips

• Review differences between weather and climate, methods of detecting climate changes, and causes of climate change.
• Understand concepts like radiative forcing, radiative damping, and the relationship to temperature stabilization.
• Be familiar with oceanic and atmospheric phenomena, such as El Niño and La Niña, and their effects on global weather patterns.

This quiz explores key concepts in climate dynamics, including Milankovitch cycles, global air circulation, the rain shadow effect, and sea breeze fronts. Understand how these phenomena impact temperature, precipitation, and seasonal variations across the globe.