Climate and Weather Notes

Weather and Climate Differences

• Weather: Short-term atmospheric conditions (rain, sunshine, wind, snow) at a specific time and place.
• Climate: Average weather patterns in a region over a long period (typically 30+ years).

Climate Zones

• Tropical: Near the equator; hot, humid, heavy rainfall.
• Dry (arid): Deserts; very little precipitation.
• Temperate: Mid-latitudes; four seasons with moderate precipitation.
• Polar/subarctic: High latitudes; cold temperatures year-round.

Wind and Global Wind Systems

• Wind: Air moving from high to low pressure areas.
• Major global wind belts:
  • Trade winds: Toward the equator.
  • Westerlies: Toward the poles.
  • Polar easterlies: From poles toward mid-latitudes.

Sea Breeze, Land Breeze, and Monsoons

• Sea Breeze: During the day, land heats faster, air rises, cooler sea air moves in.
• Land Breeze: At night, land cools faster, wind moves from land to sea.
• Monsoons: Seasonal wind systems (Asia):
  • Summer monsoon: Moist ocean air and heavy rainfall.
  • Winter monsoon: Dry air from inland regions.

High and Low Pressure Systems

• High pressure: Cold air sinks → clear skies, dry weather.
• Low pressure: Warm air rises → cloud formation and precipitation.

Types of Precipitation

1. Convectional precipitation: Hot air rises, cools, and forms rain clouds (summer thunderstorms).
2. Frontal precipitation: Warm moist air meets cold air → warm air rises over the cold air and cools, leading to precipitation.
3. Orographic precipitation: Air is forced to rise over mountains, cools, and precipitates on the windward side.

Ocean Currents

• Surface currents: Driven by global winds and Earth's rotation (Coriolis effect).
  • Example: Gulf Stream brings warm water from the tropics to northern Europe, warming the climate.
• Deep ocean currents (thermohaline circulation): Driven by differences in temperature and salinity.
  • Cold, salty water sinks and moves slowly across the globe, acting like a conveyor belt of heat and nutrients.

Weather and Climate in Norway

• Coastal climate:
  • Milder winters and cooler summers (ocean's moderating effect).
  • Higher precipitation (especially orographic rainfall).
• Inland climate:
  • Larger temperature differences between summer and winter.
  • Less precipitation (distance from the sea).

Climate Maps and Climate Diagrams

• Climate maps show the different climate zones around the world.
• Climate diagrams:
  • Red line = average monthly temperature.
  • Blue bars = monthly precipitation.
  • Useful for identifying climate types and seasonal patterns.

Global Temperature Factors

• Sun's radiation (amount varies with latitude).
• Altitude (higher altitudes = colder).
• Ocean and air currents (transport heat).
• Albedo effect: Reflectivity of surfaces (ice reflects more than dark ocean).
• Greenhouse effect: Traps heat in the atmosphere.

Greenhouse Effect

• Natural greenhouse effect: Essential for life; keeps Earth warm enough.
• Human-enhanced greenhouse effect:
  • Increased gases like $CO<em>2$, $CH</em>4$ (methane), and $N_2O$ from burning fossil fuels and agriculture trap more heat.
  • Leads to global warming and climate change.

Climate Change

• Natural causes:
  • Solar variation
  • Volcanic activity
  • Ocean current changes
• Human causes:
  • Greenhouse gas emissions from transportation, industry, deforestation, and agriculture.
• Consequences:
  • Ice melting → rising sea levels
  • More frequent and intense weather events
  • Ocean acidification
  • Species extinction
  • Droughts and floods
• Feedback loops:
  • Ice melts → less reflection → more heat absorbed → more melting.
  • Permafrost thaws → releases methane → increases warming.

El Niño and La Niña

• El Niño:
  • Warming of surface waters in the central and eastern Pacific Ocean.
  • Leads to altered rainfall patterns, droughts, and floods globally.
• La Niña:
  • Cooling of Pacific waters.
  • Often opposite effects: more hurricanes in Atlantic, wet conditions in some areas, drought in others.

Natural Disasters

• Causes:
  • Geological: Earthquakes, volcanoes, tsunamis.
  • Weather-related: Hurricanes, tornadoes, floods, droughts.
• Effects on society:
  • Loss of life and homes
  • Damage to infrastructure
  • Economic loss
  • Health and food crises
  • Poorer countries are more vulnerable due to lack of preparation

Climate Adaptation

• Actions taken to manage risks from climate change:
  • Building sea walls or flood defenses
  • Changing agricultural practices
  • Better emergency response systems
  • Urban planning and infrastructure upgrades
  • International cooperation (e.g., Paris Agreement)