Fiveable
Fiveable
You have 2 free guides left 😧
Unlock your guides
You have 2 free guides left 😧
Unlock your guides

AP Psychology

Weather and climate shape our daily lives and long-term environmental conditions. Weather is the day-to-day state of the atmosphere, while climate represents long-term patterns over decades or more.

Understanding these concepts is crucial for predicting short-term events and long-term trends. Factors like temperature, humidity, and air pressure influence weather, while global patterns and geographical features shape climate zones worldwide.

Weather vs Climate

Defining Weather and Climate

Top images from around the web for Defining Weather and Climate
Top images from around the web for Defining Weather and Climate
  • Weather refers to the day-to-day atmospheric conditions in a specific location
    • Includes temperature, humidity, precipitation, and wind
    • Can change rapidly over short periods (hours or days)
    • Examples: a sunny day, a thunderstorm, a cold front passing through an area
  • Climate describes the long-term average weather patterns and conditions in a region
    • Typically measured over a period of 30 years or more
    • Represents the expected weather conditions for a given location and time of year
    • Examples: hot and humid conditions in tropical rainforests, dry and arid conditions in deserts, cold and snowy conditions in polar regions

Comparing and Contrasting Weather and Climate

  • Weather is short-term and highly variable, while climate is long-term and more stable
  • Weather conditions can be influenced by local factors (topography, urban heat islands), while climate is determined by global factors (latitude, ocean currents, atmospheric circulation patterns)
  • Weather forecasts predict conditions for the near future (days to weeks), while climate projections estimate long-term trends and changes (decades to centuries)
  • Understanding both weather and climate is crucial for various sectors, such as agriculture, transportation, and energy production

Factors Influencing Weather

Temperature, Humidity, and Air Pressure

  • Temperature measures the average kinetic energy of molecules in the atmosphere
    • Influenced by latitude (solar radiation intensity), altitude (air density), and proximity to large bodies of water (heat capacity)
    • Affects air density, pressure, and the formation of convection currents
  • Humidity is the amount of water vapor present in the atmosphere
    • Influences the formation of clouds, precipitation, and the perceived temperature (heat index)
    • Can be measured as absolute humidity (g/m³), relative humidity (%), or dew point temperature
  • Air pressure is the force exerted by the weight of the atmosphere on a given surface area
    • Influenced by temperature (warm air rises, creating low pressure), altitude (pressure decreases with height), and the presence of high or low-pressure systems
    • Affects wind patterns, as air moves from high to low pressure areas

Wind and Atmospheric Circulation

  • Wind is the horizontal movement of air from areas of high pressure to areas of low pressure
  • Influenced by the Coriolis effect (deflection due to Earth's rotation), friction (surface roughness), and temperature differences
  • Global wind patterns, such as trade winds and westerlies, are driven by unequal heating of the Earth's surface and the resulting atmospheric circulation cells (Hadley, Ferrel, and Polar cells)
  • Local wind patterns, such as sea breezes and mountain-valley breezes, are caused by temperature differences between land and water or between mountain slopes and valleys

Air Mass Formation and Characteristics

Types and Source Regions of Air Masses

  • Air masses are large bodies of air with relatively uniform temperature and humidity characteristics
  • Originate in specific regions known as source regions, where air remains stationary long enough to acquire the properties of the underlying surface
  • Four main types of air masses:
    • Continental Polar (cP): cold and dry, originates over high-latitude land masses (Canada, Siberia)
    • Continental Tropical (cT): hot and dry, originates over arid regions (Sahara, Australian Outback)
    • Maritime Polar (mP): cold and moist, originates over high-latitude oceans (North Atlantic, North Pacific)
    • Maritime Tropical (mT): warm and moist, originates over subtropical oceans (Gulf of Mexico, Caribbean Sea)

Air Mass Modification and Interaction

  • Air masses can be modified as they move across different surfaces
    • Continental air masses become more humid as they move over water bodies
    • Maritime air masses become drier as they move over land
  • Interaction between different air masses along frontal boundaries leads to weather phenomena
    • Cold fronts: cold air mass displaces warm air mass, causing lifting and condensation (thunderstorms, heavy precipitation)
    • Warm fronts: warm air mass overtakes cold air mass, causing gradual lifting and condensation (steady precipitation, stratus clouds)
    • Stationary fronts: air masses meet but neither advances, causing prolonged precipitation and cloudiness
    • Occluded fronts: cold air mass catches up to a warm front, lifting the warm air off the ground (complex weather patterns, mixed precipitation)

Climate Zones and Weather Patterns

Major Climate Zones

  • Earth's surface is divided into three main climate zones based on latitude
    • Tropical zone: between the Tropic of Cancer and the Tropic of Capricorn (23.5°N to 23.5°S)
      • High temperatures, high humidity, and abundant rainfall throughout the year
      • Examples: Amazon rainforest, Congo Basin, Indonesian archipelago
    • Temperate zones: between the tropics and the polar regions in both hemispheres (23.5° to 66.5°)
      • Distinct seasonal changes in temperature and precipitation
      • Examples: Eastern United States, Western Europe, Eastern China
    • Polar zones: near the North and South Poles (66.5° to 90°)
      • Extremely cold temperatures, low humidity, and limited precipitation (mostly snow)
      • Examples: Arctic tundra, Antarctic ice sheet, Greenland ice cap

Köppen Climate Classification System

  • Sub-classifications within each climate zone based on temperature, precipitation, and seasonality
  • Five main climate groups: tropical (A), arid (B), temperate (C), continental (D), and polar (E)
  • Each group is further divided into sub-categories based on precipitation patterns and temperature ranges
    • Examples: Af (tropical rainforest), BWh (hot desert), Cfb (marine west coast), Dfc (subarctic), ET (tundra)
  • Provides a standardized way to describe and compare climates across different regions

Factors Influencing Climate Patterns

  • Atmospheric circulation patterns: Hadley, Ferrel, and Polar cells redistribute heat and moisture globally
  • Ocean currents: transfer heat and moisture between regions, affecting coastal climates (Gulf Stream, Kuroshio Current)
  • Distribution of land and water masses: land heats up and cools down faster than water, creating temperature gradients and influencing precipitation patterns
  • Topography: mountains can block moisture-laden air, creating rain shadows and affecting local climates (Andes, Himalayas)
  • Latitude: determines the amount of solar radiation received, affecting temperature and seasonality

Term 1 of 36

Anemometer
See definition

An anemometer is a device used to measure wind speed and direction, essential for understanding atmospheric conditions and forecasting weather. By providing crucial data on wind patterns, anemometers play a significant role in meteorology, helping to analyze the movement of air masses, predict weather changes, and study climatic variations.

Key Terms to Review (36)

Term 1 of 36

Anemometer
See definition

An anemometer is a device used to measure wind speed and direction, essential for understanding atmospheric conditions and forecasting weather. By providing crucial data on wind patterns, anemometers play a significant role in meteorology, helping to analyze the movement of air masses, predict weather changes, and study climatic variations.

© 2025 Fiveable Inc. All rights reserved.
AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.

Term 1 of 36

Anemometer
See definition

An anemometer is a device used to measure wind speed and direction, essential for understanding atmospheric conditions and forecasting weather. By providing crucial data on wind patterns, anemometers play a significant role in meteorology, helping to analyze the movement of air masses, predict weather changes, and study climatic variations.



© 2025 Fiveable Inc. All rights reserved.
AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.

© 2025 Fiveable Inc. All rights reserved.
AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.
Glossary
Glossary