Weather and Climate Notes

Introduction to Weather and Climate

  • Weather: Refers to the temporary behavior of the atmosphere, specific to a small geographic area, and can change rapidly.

    • Studied through meteorology.
    • Meteorologists are professionals who study weather patterns.

  • Climate: Describes the long-term behavior of the atmosphere, spanning over 100 years across large geographic areas, and changes very slowly.

Climate Zones

  • Polar Zone (90°-60° latitude):

    • Characteristics: Cool summers, cold year-round, and dry.

  • Temperate Zone (60°-30° latitude):

    • Characteristics: Four distinct seasons, moderate precipitation, and various climate patterns.

  • Tropical Zone (30°-0° latitude):

    • Characteristics: No winter, warm temperatures year-round, high rainfall, and humidity.

Factors Affecting Weather and Climate

  • The Sun:

    • Warms both atmosphere and oceans.
    • Creates climate zones and drives the water cycle.
    • Affects overall weather patterns.

  • The Water Cycle:

    • Evaporation: Water transforms from liquid to gas, obtaining energy from solar heat.
    • Transpiration: Evaporation from plant leaves.
    • Condensation: Air cools and water vapor turns back to liquid forming clouds.
    • Precipitation: The process when heavy water droplets fall from clouds as rain, snow, etc.
    • The ocean contributes approximately 80% of the total water vapor in the atmosphere.

Atmospheric Layers

  • Troposphere: Closest to Earth; weather phenomena occur here.
  • Stratosphere: Contains the ozone layer; characterized by stable conditions.
  • Mesosphere: Middle layer where temperatures drop significantly.
  • Thermosphere: Very hot, but has low density; extends into outer space.
  • Exosphere: Outermost layer with very low pressure and density.

Air Masses and Fronts

  • Air Masses: Large bodies of air with specific temperature and moisture characteristics (warm/cold, moist/dry).
  • Frontal Boundaries: Intersections of different air masses which can bring distinct weather:
    • Cold Front: Cold, dense air moves in, causing sudden weather changes.
    • Warm Front: Warm air replaces cold air gradually, usually bringing steady weather.
    • Occluded Front: A cold front overtakes a warm front, resulting in varied weather.
    • Stationary Front: Two air masses meet and remain in place leading to prolonged weather scenarios.

Air Pressure and Wind

  • Air Pressure: The weight of air above a certain point; measured with a barometer. Changes in air pressure indicate upcoming weather changes:

    • Falling Pressure: Indicates potential storms.
    • Rising Pressure: Suggests fair weather.

  • Winds: Created by differences in air pressure; travel from high pressure to low pressure zones. The greater the pressure difference, the stronger the wind.

    • Effects of wind are enhanced by the Coriolis Effect which causes winds to curve.

Humidity and Dew Point

  • Relative Humidity: Percentage measuring how saturated air is with moisture.

    • Warmer air holds more moisture than cooler air.

  • Dew Point: Temperature where air reaches saturation. Below freezing, it leads to frost or snow formation.

Thunderstorms

  • A mature cumulonimbus cloud triggers thunderstorms characterized by:
    • Heavy rain, potential flash floods, and possible lightning strikes.
    • Safety during thunderstorms: Stay indoors and away from electrical devices.

Tornadoes and Hurricanes

  • Tornado: A rapidly rotating column of air extending from a thunderstorm, rated from F1 to F5 based on wind speed. Tornadoes require immediate action to escape.

  • Hurricanes: Tropical cyclones categorized by wind speed. They originate over warm ocean waters, forming bands of thunderstorms and possessing an identifiable eye.

    • Hurricanes can bring extensive damage through strong winds and heavy rainfall.
    • Precautions involve preparation against high winds, flooding, and secured supplies for emergencies.