ERTH303N Terms (Part 1)

Week 1-5, ch 1, 2, 3, 13

Hypothesis

Proposed, testable explanation for something that occurs in the natural world

Theory

Well-tested and widely accepted view that best explains observable facts

Earth sphere

Atmosphere (air)

Hydrosphere (water)

Lithosphere (rock)

Biosphere (life forms)

System

Collection of numerous, independent interacting parts that form a collective whole. For example, earth is a system that is composed of interactions among its 4 spheres. Feedback loops can amplify (positive) or counteract (negative) these processes

Earth’s primordial atmosphere

Early, primary atmosphere retained from formation; hydrogen and helium dominated. Lighter elements escaped due to solar wind. Volcanic outgassing replaced these with CO2, N2, H2O, forming secondary atmosphere (4 bya)

Modern atmosphere

Retained by gravity; nitrogen (~78%) oxygen (~21%), argon (~0.9%) and trace gases like CO2, methane, and water vapor

Ozone

form of oxygen that contains three oxygen atoms in each molecule. Minimal presence in the atmosphere. Blocks UV rays in the stratosphere but acts as a pollutant in the troposphere (products of cars)

Pressure (millibar, Pa, psi)

Decreases w/ altitude. Weight of the air above us, caused by gravity pulling air molecules to Earth

Composition of atmosphere

Thermosphere, Mesosphere, Stratosphere Troposphere

Atmospheric temperature

varies significantly by altitude, decreasing from about 15°C (59°F) at the surface in the troposphere, then increasing in the stratosphere, decreasing again in the mesosphere, and rising dramatically in the thermosphere

Temp rise caused by ozone absorbing UV light

Dalton’s Law

the total pressure of a mixture of non-reacting gases is the sum of the partial pressures each individual gas would exert if it alone occupied the total volume

Perihelion and Aphelion

The point where the earth is closest to the sun in its orbit vs where it is furthest away

Ecliptic plane

imaginary, flat surface that contains Earth's orbit around the Sun

Reasons for seasons

because earth's axis is tilted at 23.5 degrees as it orbits the sun, not because of its distance from the Sun. This tilt means different hemispheres get more direct sunlight at different times of the year

Winter solstice (Dec 21)

Point when the vertical rays of the sun are directly striking the Tropic of Capricorn (winter in the northern hemisphere) resulting in the shortest day of the year

Summer solstice (June 21)

Point when the vertical rays of the sun are directly striking the Tropic of Cancer (summer in the northern hemisphere) resulting in the longest day of the year

Equinox (around March and Sept 20)

Occurs midway between solstices. The vertical rays of the run strike the equator (0 degrees) resulting in equal amounts of day and darkness, marking the start of spring or fall

Sun angle

• Solar Altitude (Elevation): angular height of the sun above the horizontal plane, ranging from at sunrise/sunset to a maximum at solar noon. It ranges from 0° (at the horizon) to 90° (directly overhead at the zenith).

• Solar Azimuth: angle between directly overhead and the sun at solar noon. For example, East is 90°, South is 180°, and West is 270°.

• Zenith Angle: The angle between the sun's position and the point directly overhead at noon. It is the complement of the altitude angle (90° - Altitude)

Analemma

plots solar declination through the year

Atmosphere selective absorber

It is not a black body because it selectively absorbs different radiation types. It reflects most

Counter radiation

LWR moving from the atmosphere to the Earth’s Surface. Causes earth to warm. The earth gives off LWR which the atmosphere absorbs, the atmosphere warms and gives off LWR

CO2 and H2O vapor are very good absorbers of LWR

clouds reflect SWR

Solar declination

Latitude at which sun is directly overhead at solar noon

Solar constant

average amount of radiation hitting the top of Earth’s atmosphere – 1367 W/m2. Earth’s surface is about 5.8 C

The sun is highest at

solar noon. It is higher in the sky in the summer than in winter

Variations in the amount of solar energy reaching a location are caused by

Seasonal changes in intensity of light (which is determined by the angle at which the sun’s rays strike earth’s surface) and by changes in the length of daylight

Insolation

Amount of solar radiation reaching a surface

Energy

capacity to do work. Described as potential (in suspension) or kinetic (motion). High temperature is associated with high kinetic energy since heat makes atoms move faster and grow hotter

energy pathways

transmission, scattering, reflection, absorption

Why earth has weather

the atmosphere and oceans are constantly trying to even out the differences between the influx of radiation at the equator and the deficit at the poles

Albedo

Amount of light reflected from the earth’s surface. High albedo (ice) means high reflection of solar radiation. Low albedo means low reflection of solar radiation (dirt, trees, etc)

Greenhouse effect

Earth's natural warming process where atmospheric gases (like carbon dioxide, methane, water vapor) trap the Sun's heat, keeping the planet habitable. Human emissions amplify this, throwing it out of the natural rhythm

Latent heat

Energy released or absorbed by a substance during a phase change without affecting its temperature

During evaporation, the energy absorbed by escaping water molecules. During freezing, the energy released by bonded molecules

EM spectrum

All visible and non-visible waves of radiation. Intensity increases with decreasing wavelength, and radiation becomes more harmful (gamma). The most intense of the sun’s rays are still in the visible light category

Radiation laws

All objects continually emit radiant energy over a range of wavelengths.

Hotter objects radiate more total energy per unit area than do colder objects.

Hotter objects radiate energy in the form of shorter-wavelength radiation than do cooler objects. Radiation emitted by Earth is often referred to as longwave radiation, whereas solar radiation is called shortwave radiation.

Objects that are good absorbers of radiation are also good emitters. Earth’s surface and the Sun are nearly perfect radiators because they absorb and radiate with nearly 100 percent efficiency. Bodies that absorb and radiate all wavelengths well are called blackbodies.

Mean, monthly, annual temp

The monthly mean temperature is calculated by adding together the daily means for each day of the month and dividing by the number of days in the month.

The annual mean temperature is an average of the 12 monthly means.

The annual temperature range is computed by finding the difference between the warmest and coldest monthly mean temperatures.

Annual and diurnal temp range

Annual temperature refers to yearly temperature cycles driven by Earth's tilt and orbit, while diurnal temperature describes daily swings from hot days to cool nights, caused by Earth's rotation and solar heating/cooling, with desert areas showing large ranges and humid coasts smaller ranges due to moisture

Isotherm

Heat map using warm or cool colors to depict temperatures

Lapse rate

rate at which atmospheric temperature decreases with increasing altitude, with steeper rates indicating instability and potential for thunderstorms, while a slower rate suggests stable conditions

Controls on global temp

latitude (angle of sunlight) is the strongest, atmospheric composition (greenhouse gases trapping heat), ocean currents, land/water distribution, elevation, prevailing winds, and surface reflectivity (albedo). Earth’s distance from the sun also plays a role

Seasonal temp change becomes more pronounced as

you move further away from the equator

The highest and lowest mean temps do not coincide with

the periods of maximum and minimum incoming solar radiation

Land surfaces are heated much more effectively than

water, because they are opaque. Water is able to redistribute heat through its larger mass

Controls on local temp

Latitude is the driving factor in temperature change, but on local scales, like how far cities are away from each other, elevation plays a larger role. Higher elevations are cooler than lower ones

Temp scales

Fahrenheit, Celsius, Kelvin

Continentality

how far inland a location is from a large body of water, with further distance resulting in a climate with greater temperature extremes (hot summers, cold winters) compared to coastal areas, because land heats and cools faster than water

Urban heat island

A city's temperature is significantly warmer than surrounding rural areas, caused by buildings, roads, and dark surfaces absorbing and re-radiating heat, reduced vegetation, and waste heat from human transport

Windchill

perceived temperature on human skin due to cold air and wind

Heat index

what the temperature feels like to the human body when relative humidity is combined with the air temperature

Growing degree days

Used to determine the day at which crops will be ready for harvest

Cooling degree days

measure the demand for air conditioning by tracking how much the average daily temperature exceeds a base of 65°F

Air pollution

Several sources, human and natural

Primary pollutants

Produced directly from identifiable sources; include particulate matter, sulfur dioxides, nitrogen oxides

Secondary pollutants

produced in the atmosphere when certain chemical reactions occur that alter primary pollutants. Secondary pollutants include sulfuric acid and the chemicals that make up smog, such as ozone and nitric acid

Particulates

tiny solid or liquid particles in the air, like dust, soot, and droplets, categorized by size (PM10 and PM2.5), with smaller PM2.5 being most dangerous as they penetrate deep into lungs, causing respiratory issues, while sources include fires, vehicles, and industry, and environmental impacts involve acid rain

Nitrogen dioxide

a strongly smelling reddish-brown gas formed from burning fossil fuels, a major contributor to smog, acid rain (forming nitric acid in water), and respiratory problems

Sulfur dioxide (primary)

About 99 percent of sulfur dioxide comes from human sources—largely the combustion of sulfur-containing fuels like coal and oil. Major sources include power plants, smelters, petroleum refineries, and pulp and paper mills. Most of the remainder comes from gases emitted during volcanic eruptions

Volatile organic compounds (VOCS)

Hydrocarbons emitted from burning fossil fuels and plant/animal matter (methane, butane, propane, octane). Reacts with NO_x to get photochemical smog

Carbon monoxide

Colorless, poisonous, odorless gas emitted from fires, incomplete fuel burning, generators, cars, grills, etc.

Lead

Dangerous even at low concentrations. Automotives used to be primary producer until lead was phased out of production, drastically reducing the amount in the atmosphere

Smog

Air pollution in urban and industrial areas. Wet and dry smog, usually product of burning sulfur. Damaging to plants/ag

Clean air act (1970)

federal law for controlling air pollution, empowering the EPA to set National Ambient Air Quality Standards (NAAQS) for common pollutants like ozone, lead, and particulate matter

Inversion

when a layer of warm air sits above cooler air near the ground, reversing the normal pattern where air gets colder with height. This stable layer acts like a lid, trapping cool air, fog, haze, and pollutants close to the surface

CFC (chlorofluorocarbon)

synthetic, non-toxic, non-flammable chemicals containing carbon, chlorine, and fluorine, once widely used as refrigerants, aerosol propellants, and solvents, but now largely phased out under the Montreal Protocol due to their devastating impact on the Earth's ozone layer

Montreal Protocol (1987)

a landmark UN treaty from 1987 to protect the ozone layer by phasing out ozone-depleting substances (ODS) like CFCs

Sulfur hexafluoride

synthetic, colorless, odorless, non-flammable gas known for its use in high-voltage electrical equipment like circuit breakers and transformers, but it's also the world's most potent greenhouse gas, with thousands of times the warming potential of CO2 and a very long atmospheric lifetime