5.2 Precipitation patterns and extreme weather events

Climate change is reshaping precipitation patterns and extreme weather events worldwide. As temperatures rise, the atmosphere holds more moisture, leading to more intense rainfall and storms. This shift affects everything from global wind patterns to ocean currents.

The impacts of these changes are far-reaching. Extreme weather events like hurricanes, floods, and droughts are becoming more frequent and severe. This poses significant risks to human societies, infrastructure, and natural ecosystems, requiring urgent mitigation and adaptation strategies.

Factors Influencing Precipitation and Extreme Weather Events

Factors influencing precipitation patterns

Top images from around the web for Factors influencing precipitation patterns

• 

  Atmospheric circulation - Wikipedia View original

  Is this image relevant?

• 

  Global Atmospheric Circulations | Physical Geography View original

  Is this image relevant?

• 

  Ocean Currents | Earth Science View original

  Is this image relevant?

• 

  Atmospheric circulation - Wikipedia View original

  Is this image relevant?

• 

  Global Atmospheric Circulations | Physical Geography View original

  Is this image relevant?

1 of 3

Top images from around the web for Factors influencing precipitation patterns

• 

  Atmospheric circulation - Wikipedia View original

  Is this image relevant?

• 

  Global Atmospheric Circulations | Physical Geography View original

  Is this image relevant?

• 

  Ocean Currents | Earth Science View original

  Is this image relevant?

• 

  Atmospheric circulation - Wikipedia View original

  Is this image relevant?

• 

  Global Atmospheric Circulations | Physical Geography View original

  Is this image relevant?

1 of 3

• Atmospheric circulation moves air masses and moisture around the globe
  • Global wind patterns driven by uneven heating of Earth's surface
    • Hadley cells circulate air between equator and 30° latitude (trade winds)
    • Ferrel cells circulate air between 30° and 60° latitude (westerlies)
    • Polar cells circulate air between 60° and 90° latitude (polar easterlies)
  • Jet streams are narrow, fast-moving air currents in upper atmosphere (polar and subtropical)
  • Monsoon systems are seasonal shifts in wind direction and precipitation (South Asia, West Africa)
• Topography influences precipitation through interaction with air masses
  • Orographic lift occurs when air is forced upward by mountains or highlands
    • Windward side experiences increased precipitation as air cools and condenses
    • Leeward side experiences rain shadow effect as descending air warms and dries (Andes, Himalayas)
  • Elevation affects temperature and moisture content of air (higher elevations are cooler and drier)
• Ocean currents transport heat and moisture, influencing regional climate patterns
  • Warm currents increase evaporation and moisture transport (Gulf Stream, Kuroshio Current)
    • Leads to increased precipitation in adjacent coastal areas
  • Cold currents decrease evaporation and create drier conditions (California Current, Canary Current)
    • Leads to arid or semi-arid climates in adjacent coastal areas
  • El Niño and La Niña are periodic shifts in ocean temperatures and atmospheric circulation patterns
    • Affect global weather patterns and precipitation distribution (droughts, floods)

Formation of precipitation types

• Rain forms through warm and cold cloud processes
  • Warm cloud processes involve coalescence of liquid water droplets
    • Collision and merging of small droplets into larger ones
  • Cold cloud processes involve ice crystal formation and growth
    • Ice crystals grow by vapor deposition and collision with supercooled water droplets
    • Bergeron process: ice crystals grow at expense of water droplets due to lower saturation vapor pressure
• Snow forms in cold clouds through aggregation of ice crystals
  • Ice crystals collide and stick together to form snowflakes
  • Shape and size of snowflakes depend on temperature and humidity conditions
• Hail forms in thunderstorms with strong updrafts and downdrafts
  • Updrafts carry water droplets and ice particles upward, allowing them to grow
  • Downdrafts carry hailstones downward, where they may be caught in another updraft and grow larger
  • Layered structure results from multiple cycles of growth and partial melting
• Sleet forms when partially melted snowflakes refreeze in a cold air layer near the surface
  • Snowflakes melt as they fall through a warm air layer aloft
  • Refreezing occurs as they encounter a cold air layer closer to the ground

Climate Change and Extreme Weather Events

Climate change and extreme weather

• Increased atmospheric moisture content due to warmer air temperatures
  • Warmer air can hold more water vapor (about 7% more per 1°C increase)
  • Leads to increased precipitation intensity and potential for heavy rainfall events
• Changes in atmospheric circulation patterns affect storm tracks and frequency
  • Shifts in jet stream position and strength can alter storm paths and intensity
  • Altered monsoon patterns can lead to changes in seasonal precipitation distribution
• Sea level rise increases risk of coastal flooding during storms
  • Higher baseline sea level exacerbates storm surge and coastal inundation
• Warmer ocean temperatures provide more energy for hurricane formation and intensification
  • Tropical cyclones feed on warm ocean waters (at least 26.5°C)
  • Increased potential for rapid intensification and higher maximum wind speeds
• Altered hydrological cycle leads to changes in drought and flood patterns
  • Increased evaporation and drought risk in some regions (Mediterranean, Southwest US)
  • Increased precipitation and flood risk in other regions (South Asia, East Africa)

Impacts of extreme weather events

• Human societies face significant consequences from extreme weather
  • Loss of life and property damage from storms, floods, and droughts
  • Displacement and migration of populations due to uninhabitable conditions
  • Economic losses from disrupted agriculture, trade, and infrastructure damage
• Infrastructure is vulnerable to damage and disruption from extreme events
  • Buildings, roads, and utilities can be destroyed or severely damaged
  • Transportation and communication networks may be disrupted, hampering relief efforts
• Natural ecosystems can be severely impacted by extreme weather
  • Habitat destruction from storms, floods, and droughts
  • Species migration and extinction due to altered environmental conditions
  • Disruption of ecosystem services, such as water filtration and carbon sequestration

Strategies for extreme weather risks

• Mitigation strategies aim to reduce the magnitude of climate change
  1. Reducing greenhouse gas emissions from human activities (energy, transportation, industry)
  2. Transitioning to renewable energy sources (solar, wind, hydro)
  3. Implementing carbon pricing and trading schemes to incentivize emissions reductions
• Adaptation strategies aim to reduce vulnerability and increase resilience to extreme events
  1. Improving infrastructure resilience through design and construction standards
  2. Developing early warning systems for storms, floods, and droughts
  3. Enhancing disaster response and recovery capabilities of communities and governments
  4. Promoting sustainable land use and urban planning practices (green infrastructure, floodplain management)
  5. Encouraging ecosystem-based adaptation measures (wetland restoration, mangrove protection)