Chapter 2 Study Guide

Chapter 2:
Key Terms

kinetic energy: An electrified region of the upper atmosphere where fairly large concentrations of ions and free electrons exist.

temperature: An electrified region of the upper atmosphere where fairly large concentrations of ions and free electrons exist.

absolute zero: A temperature reading of 273 C° ,  460 F , or 0 K. Theoretically, there is no molecular motion at this temperature.

Heat: A form of energy transferred between systems by virtue of their temperature differences.

Kelvin scale: A temperature scale with zero degrees equal to the theoretical temperature at which all molecular motion ceases. Also called the absolute scale. The units are sometimes called “degrees Kelvin”; however, the correct SI terminology is “Kelvins,” abbreviated K.

Fahrenheit scale: A temperature scale where 32 is assigned to the temperature where water freezes and 212 to the temperature at which water boils (at sea level)

Celsius scale: A temperature scale where zero is assigned to the temperature where water freezes and 100 to the temperature where water boils (at sea level).

latent heat: The heat that is either released or absorbed by a unit mass of a substance when it undergoes a change of state, such as during evaporation, condensation, or sublimation.

sensible heat: The heat we can feel and measure with a thermometer.

Conduction: The transfer of heat by molecular activity from one substance to another, or through a substance. Transfer is always from warmer to colder regions.

Convection: Motions in a fluid that result in the transport and mixing of the fluid’s properties. In meteorology, convection usually refers to atmospheric motions that are predominantly vertical, such as rising air currents due to surface heating. The rising of heated surface air and the sinking of cooler air aloft is often called free convection. (Compared with forced convection.)

Thermals: A small, rising parcel of warm air produced when Earth’s surface is heated unevenly.

Advection: The horizontal transfer of any atmospheric property by the wind.

radiant energy (radiation): Energy propagated in the form of electromagnetic waves. These waves do not need molecules to propagate them, and in a vacuum they travel at nearly 300,000 km per sec (186,000 mi per sec).

electromagnetic waves: Energy propagated in the form of electromagnetic waves. These waves do not need molecules to propagate them, and in a vacuum they travel at nearly 300,000 km per sec (186,000 mi per sec).

Micrometer: A unit of length equal to one-millionth of a meter.

Photons: A discrete quantity of energy that can be thought of as a packet of electromagnetic radiation traveling at the speed of light.

visible region: Radiation with a wavelength between 0.4 and 0.7 m. This region of the electromagnetic spectrum is called the visible region.

ultraviolet radiation (UV): Electromagnetic radiation with wavelengths longer than X-rays but shorter than visible light.

infrared radiation (IR): Electromagnetic radiation with wavelengths between about 0.7 and 1000 m. This radiation is longer than visible radiation but shorter than microwave radiation.

shortwave radiation: A term most often used to describe the radiant energy emitted from the sun, in the visible and near ultraviolet wavelengths.

longwave (terrestrial) radiation: A term most often used to describe the infrared energy emitted by Earth and the atmosphere.

Blackbody: A hypothetical object that absorbs all of the radiation that strikes it. It also emits radiation at a maximum rate for its given temperature.

selective absorbers: Substances such as water vapor, carbon dioxide, clouds, and snow that absorb radiation only at particular wavelengths.

radiative equilibrium temperature: The temperature achieved when an object, behaving as a blackbody, is absorbing and emitting radiation at equal rates.

greenhouse effect: The warming of an atmosphere by its absorbing and emitting infrared radiation while allowing shortwave radiation to pass on through. The gases mainly responsible for Earth’s atmospheric greenhouse effect are water vapor and carbon dioxide. Also called the greenhouse effect.

greenhouse gases: Gases in Earth’s atmosphere, such as water vapor and carbon dioxide, that allow much of the sunlight to pass through but are strong absorbers of infrared energy emitted by Earth and the atmosphere. Other greenhouse gases include methane, nitrous oxide, fluorocarbons, and ozone.

atmospheric window: The wavelength range between 8 and 11 m in which little absorption of infrared radiation takes place.

solar constant: The rate at which solar energy is received on a surface at the outer edge of the atmosphere perpendicular to the sun’s rays when Earth is at a mean distance from the sun. The value of the solar constant is about two calories per square centimeter per minute or about 1361 W/m2 in the SI system of measurement.

Scattering: The process by which small particles in the atmosphere deflect radiation from its path into different directions.

reflected (light):The process whereby a surface turns back a portion of the radiation that strikes it. When the radiation that is turned back (reflected) from the surface is visible light, the radiation is referred to as reflected light

Albedo: The percent of radiation returning from a surface compared to that which strikes it.

summer solstice: The point in the year when the sun is highest in the sky. Typically it occurs around June 21 in the Northern Hemisphere, with the sun directly overhead at latitude 23 1/2°N , the Tropic of Cancer.

autumnal equinox: The equinox at which the sun approaches the Southern Hemisphere and passes directly over the equator. Occurs around September 23.

winter solstice: The point in the Northern Hemisphere when the sun is lowest in the sky. Typically it occurs around December 21 in the Northern Hemisphere. At this point, the sun is directly overhead at latitude 23 1/2°S , the Tropic of Capricorn, where the summer solstice is occurring at the same time.

 vernal equinox: The equinox at which the sun approaches the Northern Hemisphere and passes directly over the equator. Occurs around March 20.

Chapter 2 Study Guide Questions    

1.   What is potential vs. Kinetic energy – how is kinetic energy defined in the atmosphere.

   1. Potential energy is stored energy of an object that is stationary. Kinetic energy is the energy of an object in motion. Kinetic energy is the electrified region of the atmosphere where ions and free electrons meet. 

2. Know the difference between warm and cold air.

   1. Warm air has more kinetic energy and collides more frequently with greater force that can cause them to spread out. Cold air has less kinetic energy and this means that the molecules collide less and are closer together.

3. What are the main differences between Fahrenheit, Celsius, and Kelvin?

   1. Kelvin scale: A temperature scale with zero degrees equal to the theoretical temperature at which all molecular motion ceases. Also called the absolute scale. The units are sometimes called “degrees Kelvin”; however, the correct SI terminology is “Kelvins,” abbreviated K. Fahrenheit scale: A temperature scale where 32 is assigned to the temperature where water freezes and 212 to the temperature at which water boils (at sea level). Celsius scale: A temperature scale where zero is assigned to the temperature where water freezes and 100 to the temperature where water boils (at sea level).

4. What are Heat Capacity and Specific Heat?

   1. Heat capacity is the amount of heat energy required to raise the temperature of an object by one degree Celsius or one kelvin. Various factors impact it such as material composition and mass. Specific heat is the amount of heat energy required to raise the temperature of one gram or one kilogram of a substance by one degree Celsius (or one kelvin).

5. Which has a higher heat capacity? Water or Land?

   1. Water has a higher heat capacity due water requiring significantly more energy to increase its temperatures to land. Land can cool and heat quickly to the specific heat theory.  

6. What is latent heat? Explain Latent heat of evaporation and condensation.  

   1. latent heat: The heat that is either released or absorbed by a unit mass of a substance when it undergoes a change of state, such as during evaporation, condensation, or sublimation. Latent heat of evaporation is the process when a liquid changes to a gas. This is the amount of energy required to do the process from liquid to gas. Latent heat of condensation is the process when gas turns into liquid. The gas molecules lose energy and slow down
      

7. Heat transfer – conduction and convection
   Conduction is the process of heat transfer through direct contact of particles in a solid material, where energy is passed from one particle to another. In contrast, convection is the transfer of heat through the movement of fluids (liquids or gases), where warmer, less dense areas rise and cooler, denser areas sink, creating a circulation pattern. This process is crucial in various natural phenomena, such as weather patterns and ocean currents.

8. What is advection?
   Advection is the horizontal transfer of heat or moisture in the atmosphere, typically occurring through the movement of air masses. This process plays a significant role in weather systems, as it can transport warm or cold air over long distances, influencing temperature and precipitation patterns.

9. What is the difference between longwave and shortwave energy?
   Longwave energy is typically associated with infrared radiation emitted by the Earth, while shortwave energy refers to the solar radiation that reaches the Earth from the sun, encompassing visible light and ultraviolet radiation. These two types of energy interact differently with the Earth's atmosphere and surface, affecting climate and weather dynamics significantly.

10. What is the EM spectrum and what are the primary types of solar and Earth radiation?
    The electromagnetic (EM) spectrum encompasses all types of electromagnetic radiation, ranging from radio waves to gamma rays. The primary types of solar radiation include ultraviolet (UV), visible light, and infrared (IR), while Earth radiation primarily consists of longwave infrared radiation that is emitted back into the atmosphere after absorbing solar energy. Understanding these differences is crucial for comprehending how energy transfer processes affect weather patterns and climate change.

11. What is the Greenhouse effect? Natural? Man-made?
    The greenhouse effect is a natural process that warms the Earth’s surface. When the sun's energy reaches the Earth, some of it is reflected back to space and the rest is absorbed, warming the planet. Greenhouse gases, such as carbon dioxide and methane, trap some of this heat in the atmosphere, preventing it from escaping. While this effect is essential for maintaining a habitable climate, human activities, particularly the burning of fossil fuels and deforestation, have significantly increased the concentration of these gases, enhancing the greenhouse effect and contributing to global warming.

12. What is albedo? What is the average Earth albedo? Which surfaces have high albedos?

    Albedo is a measure of the reflectivity of surfaces, indicating how much sunlight is reflected back into space without being absorbed. The average Earth albedo is approximately 0.3, meaning that about 30% of incoming solar radiation is reflected back. Surfaces with high albedos include snow, ice, and light-colored deserts, which reflect more sunlight compared to darker surfaces like forests and oceans. In addition, urban areas with buildings and roads often exhibit lower albedos due to their darker surfaces, contributing to the urban heat island effect.