Lecture 6 - Atmosphere and Surface Energy Balances & Global Temperatures Flashcards
Define Earth’s energy balance.
The balance between solar radiation inputs (insolation) and outputs of the earth (radiation to space).
What are the types of radiation involved in Earth’s energy balance?
Shortwave radiation inputs (UV, visible light, near-infrared wavelengths) and longwave radiation outputs (thermal infrared wavelengths).
Define transmission.
The uninterrupted passage of shortwave and longwave energy through either the atmosphere or water vapour.
Define heat.
The flow of kinetic energy between molecules and from one body or substance to another resulting from temperature difference between them.
Define sensible heat and latent heat.
Sensible heat can be sensed by humans as temperature, while latent heat is the energy gained or lost when a substance changes from one state to another.
What are the methods of heat transfer?
Radiation, conduction, and convection.
What is Wien’s Law?
The hotter the object, the shorter the wavelengths emitted.
Define conduction.
The molecule-to-molecule transfer of heat energy as it diffuses through a substance.
Define convection.
The transfer of heat by physical mixing or circulation, usually involving a strong vertical motion.
Define advection.
The transfer of heat by physical mixing or circulation, usually involving a strong horizontal motion.
Give examples of heat transfer in the physical environment.
Radiation and conduction: temperature differences between land and water bodies and heating/cooling of soil layers. Convection: atmospheric and oceanic circulation and air mass movements. Advection: horizontal movement of winds from land to sea.
Define scattering.
Insolation that is reflected back into space.
Define diffuse radiation.
Energy that reaches the Earth’s surface after scattering – casts shadowless light on the ground.
What is Rayleigh’s Scattering Principle?
Shorter wavelengths are scattered more (blues and violets making the sky appear blue), while longer wavelengths are scattered less (oranges and reds).
What is Mie Scattering?
When the solar radiation encounters larger particles in the air, like cloud droplets, dust or pollutants, all wavelengths of visible light are scattered evenly.
Define refraction.
The bending that occurs as insolation passes through different mediums - the insolation changes speed and shifts its direction (bending).
Define reflection and albedo.
Reflection is a portion of arriving energy that bounces directly back into space, while albedo is the reflective quality of a surface, measured as the percentage of insolation that is reflected.
Define absorption.
The assimilation of radiation by molecules of matter, converting the radiation from one form of energy to another.
What happens to incoming solar radiation?
31% is reflected, 45% is absorbed by land and water surfaces, and 24% is absorbed by atmospheric gases, dust, clouds, and stratospheric ozone.
How do atmospheric gases selectively absorb radiation?
Oxygen and ozone absorb shortwave UV radiation, and carbon dioxide and water vapour absorb longwave radiation emitted by the Earth. None absorb wavelengths of visible light.
How do aerosols affect atmospheric albedo?
The volcanic eruption of Mt. Pinatubo injected sulfur dioxide droplets in the atmosphere, cooling the Earth.
Define global dimming.
Pollution-related decline in insolation to the Earth’s surface.
What is the “Greenhouse Effect”?
The passage of longwave radiation into space is delayed as it is absorbed by certain gases, clouds, and dust in the atmosphere, then reradiated back toward the Earth, increasing the temperature in the troposphere over time.
What role do clouds play in the Earth’s energy balance?
Clouds can perform a dual function, cooling and warming, depending on cloud cover, type, altitude, and thickness.
