ENVS 101 1st EditionExam # 3 Study Guide Lectures: 18 - 27Lecture 18 (March 7)Universal Gas Law: PV-nRT - Pressure, Volume, Number of molecules, and Temperature of a gas are related. In this equation, R is a constant. As one value changes, the others will respond (see saw effect)- As air is blown into a balloon, how do P and V change? Both undergo an increase!Evaporation absorbs heat, and this energy is stored in water vapor, and called latent heat- Condensation releases latent heat, providing energy for storms (bear in mind that because energy can neither be created nor destroyed, latent heat is a form of potential energy). When the air is cold and dry, there is not much energy in the atmosphere. During the summer however, humidity will increase, and this is the energy that fuels occurrences such as storms throughout the Earth.- Absolute Humidity- Amount of water vapor in the atmosphere (i.e about 0-4% of air, dew point, or a partial pressure measurement)When the number of molecules that evaporate equals the number that condense, the vapor is saturated. - Relative Humidity- amount of water as a fraction or % of the saturation value (this is influenced by both water vapor as well as temperature.- Dew Point: temperature at which an air mass becomes saturated. Cooling air to the dewpoint causes condensation of clouds, fog, or dew. Evaporation and condensation are influenced by temperature, higher temperatures favor evaporation over condensation.Adiabatic Lapse Rate: PV=nRT- Warm air rises, but since air pressure decreases, the air expands and cools- Cool air descends, but with increased air pressure it compresses and warms- The rate of temperature change with change in elevation is the:o Dry adiabatic lapse rate (unsaturated air)o Moist adiabatic lapse rate (saturated air) cooling occurs slower as latent heat is released by condensation.Clouds are visible aggregates of minute water droplets, ice crystals, or both. They form when airrises and becomes saturated with moisture, a response to adiabatic cooling and condensation. Cloud drops require condensation nuclei (consisting of dust and aerosols) to condense onMoisture in the Atmosphere: Cumulus are puffy individual clouds, Stratus are sheets of cloud cover, Cirrus are the highest, wispy feathers composed of ice crystals, Nimbus are rain, as in cumulonimbus or nimbostratus. Cloud bases will show the condensation level.Lecture 19 (April 2)1. Density lifting: Convection Processa. Unstable air (cold over warm)-> convectionb. Stable air (cool over warm)-> minimal lifting and fair weather cloudsc. Temperature inversion (warm over cool)-> no convection, trapping of pollution atthe surface2. Fontal liftinga. Front is the boundary between a warm and a cold air massb. Air mass movement causes warmer air to risec. Warm Fontd. Cold Front3. Orographic liftinga. Flowing air is forced upward due to terrain b. Rain on windward side (facing the wind)c. Rain shadow (dry, dessert) on leeward side (away from the wind)4. Convergence liftinga. Flowing air masses converge and are both forced upwardsSea Breeze/Land Breeze- Near coasts, the land heats up more rapidly than the sea during the day, o Rising warm air generates a low pressure system, often with clouds or raino Air moves in on the pressure gradient creating a sea breezeo An upper level reverse flow sets in, forming a convection cell- During the night, heat is radiated more rapidly from the land and the situation reverses, creating a land breezeKeep in mind that land has a lower heat capacity than water does, which means it takes less energy (as well as time) to heat up land by 1oC than it would to heat up water by the same amount.Weather is the state of the atmosphere at a given time and place, determined by five variables:1. Temperature2. Air pressure3. Humidity4. Cloudiness5. Wind speed and directionClimate is long term, average weather- Wind is caused by differences in air pressure: Wind flows from areas of high pressure to areas of low pressure.Most places have wind speeds that average between 10 and 30 km/hour (6-20mph)In places where temperature drop below freezing, the windchill factor is reported.o Wind increases evaporationo Windchill factor is the temperature it “feels like” to exposed skin given the air temperature and wind speedWind speed and direction are affected by: 1. Pressure gradient force: A drop in air pressure per unit of distance, higher pressure gradient leads to a higher wind speed as a result.2. Coriolis force: the deviation from a straight line of the path of a moving body as a result of Earth’s rotation.3. Friction: the resistance to movement from contact (slows the wind)With the Pressure-gradient force: Isobars, lines of equal air pressure on a weather map. Isobars close together show a steep gradient, and isobars that are far apart show a low gradient. A steep gradient shows a faster change in pressure, and low gradient indicates a slower change.Geostrophic Winds: Eventually the pressure gradient force and the Coriolis effect are in balance, and the wind flows parallel to the isobars.o Low-pressure centers develop an inward spiral motion (convergence, lifting, cyclone)o Northern Hemisphere: counter-clockwise movement o High-pressure centers develop an outward spiral motion (divergence, sinking, anticyclone) Northern Hemisphere: clock-wise motiono The rotation is reversed in the Sothern HemisphereThe Equator receives more of the Sun’s energy, this difference in energy drives global circulationpatterns.Lecture 20 (April 7) Throughout nature, there are various other organisms that act as climate proxies to help scientists study the climate of the Earth. Organisms that lay down annual growthrings such as trees and corals are commonly used to study climate change, as well as some lake sediments which form pairs of layers that are deposited in a single year, (known as varves).Lecture 21 (April 9) Precession of the equinoxes: The direction Earth’s axis points moves in a circle. This process changes the season when Earth is closest to the sun (right now we are closest during our winter season). This procession has a time period of around 23,000 years.External causes are too small to account for the average global temperature changes. The variations that occur must be amplified by internal feedbacks.- A change that occurs in one of Earth’s subsystems will end up causing another change ina different subsystem as a result. The change may become amplified as it