climate as a global system Flashcards
What is global atmospheric circulation?
A worldwide system of winds that transfers solar heat energy from the equator to the poles to balance Earth’s temperature.
How is wind formed?
Wind is caused by air moving from high-pressure areas to low-pressure areas due to uneven heating of the Earth’s surface by the Sun.
Why does the equator receive more heat than the poles?
The Sun’s rays strike the equator more directly, whereas at the poles they spread over a larger area due to the Earth’s curvature and tilt.- milancovich cycle
What process causes warm air to rise and cool air to sink?
Convection.
What creates atmospheric pressure cells?
Uneven heating of the Earth’s surface creates differences in air pressure, forming pressure cells.
Name the three atmospheric circulation cells in each hemisphere.
Hadley Cell, Ferrel Cell, and Polar Cell.
What is the Hadley cell and what weather does it create?
It is the largest cell (from the equator to ~30–40° N/S). Rising air near the equator causes thunderstorms; sinking air at subtropics causes dry, hot desert climates.
How does the Ferrel cell behave?
It circulates air from ~30° to ~60° N/S, moving opposite to the Hadley and Polar cells, creating unsettled, changeable weather (e.g., in the UK).
What happens in the Polar cell?
Cold air sinks at the poles (creating high pressure), flows towards lower latitudes, slightly warms, rises, and returns aloft to the poles.
What is the Coriolis effect?
The deflection of winds due to Earth’s rotation—winds curve right in the Northern Hemisphere and left in the Southern Hemisphere.
What are trade winds?
Surface winds blowing from subtropical high-pressure areas (around 30°) toward the equator, deflected west by the Coriolis effect.
What are westerlies?
Winds blowing from subtropical highs to mid-latitudes (30°–60°), deflected east by the Coriolis effect.
What are polar easterlies?
Cold winds that blow from the poles and meet the westerlies at around 60° latitude.
Why does the UK experience frequent wet and windy weather?
The UK lies in the mid-latitudes under the influence of the Ferrel cell, where westerly winds and low-pressure systems from the Atlantic dominate.
What is another name for the ocean conveyor belt?
Thermohaline circulation.
What drives thermohaline circulation?
Differences in temperature and salinity: cold, salty water sinks at the poles, drawing in warmer surface water.
What weather conditions are caused by subsidence (sinking air)?
High pressure, clear skies, dry/arid weather, and little precipitation.
What weather conditions are caused by convection (rising air)?
What weather conditions are caused by convection (rising air)?
How do the sea and land affect seasonal pressure?
Sea: High pressure in summer, low in winter (heats/cools slowly).
Land: Low pressure in summer, high in winter (heats/cools quickly).
Why is the pattern of global pressure belts not symmetrical?
Because the uneven distribution of land and sea shifts pressure zones, even though atmospheric cells mirror each other in both hemispheres.
