Climate Change in the Tropics Vocabulary

Climate Change in the Tropics: Quiz 1 Topics Lecture 1 to 4

Weather and Climate

• Weather: The condition of the atmosphere at any given time and place.
• Climate: The collective pattern of weather over many years, representing long-term atmospheric conditions over a span of 20-30 years.

Climate Systems

• Climate System: A complete system composed of interlocking subsystems, each with unique characteristics such as albedo and specific heat.

Principal Components of Earth’s Climate System

• Insolation: Incoming solar radiation.
• Earth's Energy Balance: Imbalance created by energy surpluses at the equator and deficits at the poles causes global circulation of winds and ocean currents.
• Temperature:
  • Primary controls are latitude, elevation, cloud cover, and land-water heating differences.
  • Global winds, ocean currents, and air masses impact global temperature.
• Air Pressure:
  • Winds flow from areas of high pressure to low pressure.
  • Low pressure at the equator creates a belt of wet climates.
  • High pressure in subtropical regions creates areas of dry climate.
• Air Masses: Vast bodies of homogenous air that form over oceanic and continental source regions, taking on the characteristics of the region. As these air masses migrate, they carry their temperature and moisture to new regions.
• Atmospheric Moisture: Movement of water through the hydrologic cycle affects weather and ultimately determines climate.

Classification of Earth’s Climates

• Classification: The ordering or grouping of data or phenomena into categories of varying generality.
• Köppen Climate Classification: A widely recognized climate classification system based on precipitation and temperature.
  • Köppen-Geiger Climate Classification uses a 3-letter system:
    • 1st: differentiates between dry and moist climates, divided by temperature.
    • 2nd: indicates the degree of aridity (availability of water) or temporal distribution of precipitation.
    • 3rd: represents seasonal variation.
• Importance of Classification:
  • Determines suitable crop types and understanding soil types.
  • Informs heating/cooling requirements for housing.
  • Essential for the construction business and most economic activities.
  • Provides insight into processes that act to create the climate region.

Subcategories of the Six World Climate Groups

• Tropical: (tropical latitudes) - Most extensive.
• Mesothermal: (midlatitudes, mild winter) - Mild winters, warm and temperate and experience seasons.
• Microthermal: (mid and high latitudes, cold winters).
• Polar: (high latitudes and polar regions).
• Highland: (high elevations at all latitudes) - Highlands have lower temperatures.
• Dry: (permanent moisture deficits).

Pathways for Solar Energy to Earth’s Surface

• Solar energy is generated by fusion.
• Radiant Energy: Energy released from the sun which travels through space in electromagnetic waves.
• All objects radiate energy in wavelengths related to their surface temperatures.
  • The hotter the object, the shorter the wavelength; the cooler the object, the longer the wavelength.
• The Sun emits shortwave energy, and Earth emits longwave energy.
• Only a fraction of the insolation entering the atmosphere reaches the surface.
• The rest is either reflected back out to space or absorbed by Earth’s atmosphere.
• Insolation that reaches Earth’s surface arrives as either direct or diffuse radiation (Roughly half of the total insolation received at the top of the atmosphere reaches Earth’s surface).
• Scattering: Atmospheric molecules physically interact with insolation to redirect radiation, changing the direction of the radiation’s movement without altering its wavelengths (Rayleigh and Mie).
  • Diffuse Radiation: Arrives at Earth’s surface by scattering and is how we experience “daylight” on a completely overcast day.
• As insolation passes from one medium to another, its speed and direction change, a process called refraction.

Albedo

• Albedo: The percentage of insolation that is reflected, is an important control.
  • Described as the “reflective quality, or intrinsic brightness, of a surface.”
  • 0% means all light is absorbed.
  • 100% means all light is reflected.
• \text{Reflection} = \text{Albedo}
• Darker-colored surfaces have LOWER albedos, and lighter-colored surfaces have HIGHER albedos.
• On water surfaces, the angle of sunlight impacts albedo: lower angles produce MORE reflection than higher angles do.
• Earth's Average Albedo is 31%.

Effect of Greenhouse Gases, Clouds, and Aerosols on Atmospheric Heating and Cooling

• Greenhouse Gases: Gases that are mostly transparent to the passage of shortwave solar radiation but effective at absorbing longwave infrared radiation emitted by Earth and the atmosphere.
  • They raise temperature, stabilize, and globalize temperature.
• Clouds: Longwave radiation is ABSORBED by clouds and certain gases in the lower atmosphere and then EMITTED to space or RERADIATED back to the surface.
  • This process delays longwave energy losses to space and acts to warm the lower atmosphere.
• Aerosols

Earth–Atmosphere Energy Balance and Patterns of Net Radiation at the Surface

• Review the Earth–atmosphere energy balance and the patterns of net radiation at the surface.

Additional Notes

• Conduction is the process where molecule-to-molecule transfer of heat takes place.