Physical Geography Section 1 -

Spatial

Space. the nature or character of physical space.

Spatial science

A field that studies the patterns, relationships, and processes of our environment and society.

Location

Where something is on Earth (5 themes of Geography)

Place

The characteristics that make an an area on Earth unique (5 themes of Geography)

Region

Any area that displays some unity of traits or characteristics. A region can involve human geography but also physical geography. (5 themes of Geography)

Movement

Everything moves and nothing ever stays the same. It happens all the time. (5 themes of Geography)

Human-environment Interaction

A back and forth between humans and the environment. Humans impact their environment and vice versa. (5 themes of Geography)

Absolute location

A specific location that you can pinpoint

Relative location

A way to describe where something is without using absolute location (AKA relative)

Geography

The study of places, the Earth's surface, and the relationships between people and their environments

Physical geography

the branch of geography that studies the Earth's natural features, surface processes, and patterns in the environment.

Human geography

the study of how human societies develop, interact with their physical environments, and organize across Earth's space.

Earth Systems Science

The study of our planet as an integrated, complete (holistic) system made of interacting physical, chemical, biological, and human components.

4 Spheres of the Earth System

1. Atmosphere → air

2. Hydrosphere → water

3. Lithosphere → earth

4. Biosphere → Life

Geographic Grid

A grid that circumferences the Earth’s surface that allows a really exact depiction of a location even when there’s no place name.

Latitude

The angular distance North and South of the Equator.

Longitude

The angular distance East and West of the Prime Meridian.

Parallels

The horizontal lines that span the entire globe west to east to represent points of equal latitude. (0-90° from either side of the Equator)

Meridians

Lines that span the entire globe from North to South and all converge to a single point at the Poles along the Prime Meridian. (0-180° degrees)

Equator

An imaginary line around the middle of the Earth that lies halfway between the North Pole and the South Pole, splitting the planet into two equal halves that is the Northern and Southern hemispheres. (0° latitude)

Prime Meridian

An imaginary line that divides the Earth into the Western and and Eastern hemispheres. The Prime Meridian runs through Greenwich, England at 0° longitude.

International Dateline

An imaginary line along Earth that divides two consecutive calendar days, located at 180° longitude.

Great Circle

Any circle that divides the Earth into a circumference of two equal halves. For navigation, the arc of great circles will give you the shortest distance between any two locations on the surface of Earth.

Small Circle

Circles that divide a sphere into unequal portions (AKA not two equal halves). Anything other than a great circle is a small circle.

North and South Poles

The two opposite ends of the Earth where its axis of rotation meets its surface. The North Pole is located at 90°N latitude and the South Pole is located at 90°S latitude.

Revolution

The movement of the Earth around the sun (the orbit). (Earth-Sun relationship)

Rotation

The movement of the Earth around its axis. (Earth-Sun relationship)

Axis

The imaginary line that runs through the center of the Earth between the North and South poles

Perihelion

The time of the year when Earth is closest to the Sun

What date does the Perihelion occur and how far away is it?

On/around January 3rd, with the distance being 91.5 million miles away.

Aphelion

The time of the year when Earth is farthest from the Sun.

What date does the Aphelion occur and how far away is it?

On/around July 4th with the distance being 94.5 million miles away.

Plane of the Ecliptic

The constant imaginary plane about which the Earth orbits the Sun. It bisects the Earth and the Sun, allowing for perfect orbit around the Sun. (0°).

Plane

A flat, two-dimensional space that extends indefinitely.

Axial Tilt

The Earth’s axis is tilted 23.5° from the perpendicular (meeting or intersecting at a 90° right angle) to the Plane of the Ecliptic. (Earth-Sun relationship)

Parallelism

Also referred to as Polarity, it means the Earth’s axis is always pointing in the same direction, at the same degree of tilt, regardless of where it is in its revolution. As a result, only half of the Earth is lit at any given time. (Earth-Sun relationship)

Circle of Illumination

The imaginary line that divides the illuminated, daytime half of the Earth from the dark, nighttime half.

Equinox

A twice-a-year event when the Sun is directly above the Earth’s equator, splitting daylight and darktime hours equally in half (12 daylight hours and 12 nighttime hours).

When are the Equinoxes?

March 20-21st and September 22-23rd.

Solstice

A twice-a-year event when the sun is at its farthest point North or South of the Equator, resulting in the year’s longest or shortest days.

When are the Solstices?

June 21-22nd and December 21-22nd.

Impact of the Solstices at the Poles

At the June Solstice, the North Pole experiences 24 hours of daylight while the South Pole experiences 24 hours of darkness. At the December solstice, the North Pole experiences 24 hours of darkness and the South Pole experiences 24 hours of daylight.

Insolation

The amount of solar radiation that reaches the Earth → INcoming SOLar radiATION.

Subsolar point

The exact spot on Earth's surface where the sun sits directly overhead at a 90-degree angle. The subsolar point is always located on the Tropics (up to 23.5° N or S) or somewhere between them.
- At the solstices, the subsolar point is either on the Tropic of Capricorn or Cancer.
- At the equinoxes, the subsolar point is at the equator (0°).

Tropic of Cancer

An imaginary circle of latitude located at approximately 23.5° north of the Earth's equator. The subsolar point hits along this line of latitude at the June solstice.

Tropic of Capricorn

An imaginary circle of latitude located at approximately 23.5° south of the Earth's equator. The subsolar point hits along this line of latitude at the December solstice.

The Arctic Circle

An imaginary line of latitude at approximately 66.5° North of the equator. Anywhere ABOVE this line, the sun will not set (24 hours of daylight) on the June solstice (June 21-22nd) and will not rise (24 hours of darkness) on the December solstice (December 21-22nd).

The Antarctic Circle

An imaginary line of latitude at approximately 66.5° South of the equator.
Anywhere BELOW this line, the sun will not rise (24 hours of darkness) on the June solstice (June 21-22nd) and will not set (24 hours of daylight) on the December solstice (December 21-22nd).

Climate Zonation

The division of the Earth’s surface into distinct latitudinal or regional bands based on similar long-term weather patterns, temperature ranges, and precipitation levels.

The divisions include:

• Tropical Zone

• Polar Zone(s)

• Mid-latitude (Temperate) Zone(s)

Tropical Zone

From tropic to tropic/30 N to 30 S that experience warm to hot temperatures year-round.

Polar Zone

From Arctic circle and up/Antarctic circles and down (60 N and up and 60 S and down), they experience cool to cold summers and cold to frigid winters.

Mid Latitude (Temperate) Zone

In between Tropical and Polar zones, they experience cool to cold winters and warm to hot summers.

Radiation

The transfer of heat or energy through electromagnetic waves without needing any matter or medium. (Forms of Energy Transfer)

Convection

The transfer of heat through the movement of fluids like liquids or gases.

• When you heat up a fluid, the molecules move and mix around, getting more excited, decreasing its density, and causing the heated molecules to rise while the cooler, denser molecules sink. This process is known as a convection current.

(Forms of energy transfer)

Conduction

The transfer of heat and thermal energy through direct physical contact. (Forms of energy transfer)

Advection

The transport of a substance, heat, or other property by the bulk motion of a fluid like air or water.

The Electromagnetic Spectrum

The complete range of all types of electromagnetic radiation, organized by wavelength, frequency, energy, and even temperature.

• The wavelengths are related to the temperature at which objects radiate most of their energy. The hotter something is, the shorter the wavelength. The cooler something is, the longer the wavelength.

• Radio → Microwave → Infared → Visible → Ultraviolet → X-ray → Gamma

Radio waves

Radio waves are a type of electromagnetic radiation with the longest wavelengths and lowest frequencies in the electromagnetic spectrum.

Microwave waves

A. type of electromagnetic radiation with wavelengths that are longer than infrared light but shorter than ordinary radio waves.

Infared waves

A type of invisible electromagnetic radiation with wavelengths longer than visible red light but shorter than microwaves.

• Humans/animals radiate energy in the infared.

Visible spectrum

The wavelengths our eyes can actually see.

• The colors depicted in the visible spectrum follow the acronym ROYGBIV → Red, orange, yellow, green, blue, indigo, and violet

• Following the rules of electromagnetic spectrum, red wavelengths will be longer than violet wavelengths (and also cooler)

Ultraviolet waves

A form of electromagnetic radiation with wavelengths shorter than visible violet light but longer than X-rays.

X-ray waves

A form of high-energy electromagnetic radiation with wavelengths shorter than ultraviolet light and longer than gamma rays.

Gamma waves

The most energetic form of electromagnetic radiation, featuring the shortest wavelengths and highest frequencies on the electromagnetic spectrum.

Solar constant/TSI (Total Solar Irradiance)

The amount of solar radiation that reaches our atmosphere from the Sun

• Only about half of the total amount of TSI reaches the Earth’s surface after passing through the atmosphere

Atmosphere

The blanket/layer of gases that surround the Earth

• 3 of the gases make up 99.9% of all gases in the composition of the dry atmosphere:

  • Nitrogen (N₂) = 78%

  • Oxygen (O₂) = 21%

  • Argon (Ar) = 0.9%

• While the visible spectrum can pass through Earth’s atmosphere, most of the other solar energy does not make it

Trace gases

Gases that make up less than 1% of the Earth’s atmosphere

• Carbon dioxide (CO₂) = 0.04%

  • CO₂ is anthropogenic and consequently is continuously increasing

  • It is also referred to as >400 ppm (parts per million)

• Water (H₂O) = 0-1% to 3-4% → ~~2%

  • Water is HIGHLY VARIABLE depending on location (think humidity), hence why it’s not included in the composition of the atmosphere

  • In the polar regions, H₂O will account for 0-1%, while in tropical regions, it will account for 3-4% of all gases in the Earth’s atmosphere

• Ozone (O₃),

Anthropogenic

Caused, created, or influenced by human activity

Shortwave radiation

Radiant energy emitted by the Sun that includes ultraviolet, visible light, and near-infrared wavelengths

• Shortwave radiation is hot and emitted by the Sun

Longwave radiation

The thermal infrared energy emitted by the Earth's surface and atmosphere.

• Longwave radiation is cool and emitted by the Earth. Longwave radiation is then emitted by the lower atmosphere after the gases within it absorb the longwave radiation emitted by the Earth.

• It is only the trace gases trapping the “radiant heat” AKA absorbing longwave radiation and keeping us warm. Those gases are called greenhouse gases as a result.

Absorption

The process in which gases in Earth’s atmosphere absorb incoming solar radiation.

• Ozone (O₃) absorbs UV radiation

• Other greenhouse gases

• If something absorbs all wavelengths, it appears black

(Reasons solar energy does not pass through the atmosphere)

Function of Ozone (O₃)

Ozone absorbs UV radiation, which has different wavelengths: UVa, UVb, UVc

• UVa passes through Earth’s atmosphere pretty well and is fairly harmless

• A lot of UVb gets absorbed by the atmosphere and some makes it down to Earth

  • UVb are the UV rays that give you sunburns, cause DNA damage, and cause cancer in animals, humans, and even plants alike

• UVc gets completely absorbed in the atmosphere

The amount of ozone in the atmosphere changes with altitude

• In the stratosphere, the amount of ozone increases, which is referred to as the Ozone Layer

(KNOW THE IMAGE’s BASIC CURVE)

The Ozone Layer

A protective region in Earth's stratosphere that absorbs most of the sun's harmful ultraviolet (UV) radiation

• The saying “there’s a hole in the Ozone Layer” refers to the lack of ozone/the fact there is far less ozone within the layer than should be, allowing more UV radiation through and raising a big concern

• The Ozone Layer is found within the stratosphere between 9 to 19 miles altitude

  • The thickness of the ozone layer varies by the season and also by latitude

• The ozone layer is extremely important because ozone gas in the stratosphere absorbs most of the harmful UV radiation and consequently protects life on Earth

Reflection

The process where incoming solar radiation bounces back into space when it hits gases and particles in the Earth’s atmosphere

• Clouds are one of the best things to reflect the sun’s energy

• If something reflects all wavelengths, it appears white

(Reasons solar energy does not pass through the atmosphere)

Scattering

The process where gases and particles in the Earth’s atmosphere redirect incoming solar radiation in all directions

• Nitrogen (N₂) and oxygen (O₂) are pretty good at scattering the blue wavelengths of the visible spectrum, which is why the sky appears blue to our eyes

(Reasons solar energy does not pass through the atmosphere)

Refraction

The process where when waves of energy enter a certain medium (like gas molecules), they can bend, meaning they alter direction

(Reasons solar energy does not pass through the atmosphere)

Diffuse radiation

When the earth’s energy does not hit directly on the Earth

• When there is scattered and refracted wavelengths, the Sun’s energy is not directly hitting something on Earth and instead coming from different directions → this is classified as diffuse radiation

• You can see inside a shadow because of diffuse radiation (the light being scatted from different directions)

Direct radiation

When the sun’s energy hits the Earth directly without being scattered or blocked by gases or other particles in the Earth’s atmosphere

• When you block direct radiation with an object, you get a shadow

• Clouds keep a lot of direct radiation from hitting the Earth

Albedo

The reflecting quality of something

• Various surfaces have different reflective qualities (EX: Mirrors have perfect albedo)

• Albedo is given in percent (0-100%) → (EX: 100% albedo means something reflects 100% of the sun’s energy)

• Snow and clouds have high albedo which is why they appear white since they’re reflecting a lot of the sun’s light (EX: Snow’s albedo is 80-90%)

  • The temperatures during snow stay cooler since it is mostly not absorbing the sun’s energy to heat up and melt

• Blacktop concrete has 5-10% albedo because black surfaces absorb way more energy and consequently heat up more

Troposphere

The lowest and densest layer of Earth's atmosphere, extending from the surface up to about 5 to 11 miles (8 to 18 kilometers) high.

• The temperature decreases with increasing altitude.

• On average, the temperature gradient of the troposphere is 6.5 C° per 1,000 m (3.5 F° per 1,000 ft.) of altitude.

• This layer accounts for the weather we experience on Earth.

• It holds about 80% of the atmosphere's total mass and 99% of its water vapor.

• Tropo = turn, because the air in the troposphere does a lot of mixing (AKA warm air near the surface of the Earth rises and cool air higher in the troposphere sinks)

  • At the top of the troposphere is a thin layer in which the temperature does not change with height

• Air between the troposphere and stratosphere rarely mix

Stratosphere

The second-lowest major layer of Earth's atmosphere, located directly above the troposphere and below the mesosphere.

• It begins roughly 6 to 10 miles above Earth's surface and extends up to around 31 miles

• In the stratosphere, temperature increases with altitude.

• The direct heat source for the stratosphere is the Sun

  • Air in the stratosphere is stable because warmer, less dense air sits over cooler, dense air

  • Once in the stratosphere, particles (EX: ash and gas from a large volcanic eruption) may stay suspended there for many years because there is so little mixing between the stratosphere and tropospher

• The Ozone Layer is found within the stratosphere between 9 to 19 miles altitude

Mesosphere

The third layer of Earth's atmosphere, located directly above the stratosphere and below the thermosphere

• Its altitude range extends from about 31 to 53 miles above Earth's surface.

• Temperatures in the mesosphere decrease with altitude.

  • Because there is so few gas molecules in the mesosphere to absorb the Sun’s radiation, the heat source is the stratosphere below.

• The mesosphere is extremely cold, especially at its top, about -90 °C (-130 °F).

• The air in the mesosphere has extremely low density → 99.9% of the mass in the atmosphere is below the mesosphere.

  • As a result, the air pressure is very low.

Thermosphere

A high-altitude layer (4th layer) of Earth's atmosphere located directly above the mesosphere and below the exosphere, beginning at 50 to 56 miles above Earth's surface and extending up to between 311 and 621 miles.

• The density of molecules is so low in the thermosphere that one gas molecule can go about 1 km before it collides with another molecule

  • Despite the high temperatures, it would feel very cold because there is so little energy being transferred

• Temperatures increase sharply with altitude.

  • Temperatures often reach from 2,000°C up to 2,500°C (3,600°F to 4,500°F) or more due to the absorption of high-energy X-rays and UV radiation from the Sun

• Within the thermosphere is the ionosphere

Ionosphere

• It gets its name from the solar radiation that ionizes gas molecules to create a positively charged ion and one or more negatively charged electrons

  • The freed electrons travel within the ionosphere as electric currents

• Because of the free ions, the ionosphere causes radio waves to bounce off of it at night back to Earth

  • This is why you can often pick up an AM radio station far from its source at night

• Another feature of the ionosphere are the Van Allen radiation belts, which are two doughnut-shaped zones of highly charged particles that are located beyond the atmosphere in the magnetosphere

• The ionosphere is responsible for night-time auroras (thanks to overcharging the Van Allen radiation belts)

Exosphere

the highest and outermost layer of Earth, acting as the fuzzy boundary where the atmosphere thins out and merges with outer space. It is above the thermosphere.

• There is no real outer limit to the exosphere, but it starts at about 310 to 620 miles (500 to 1,000 km) above Earth's surface

Solar wind

A continuous stream of charged particles—mostly protons and electrons—that travel rapidly outward from the Sun. This is beyond the atmosphere

Environmental Lapse Rate (ELR)

The actual, observed decrease in air temperature with increasing altitude at a specific time and location in the troposphere

• The ELR is determined by a radiosonde, an instrument carried by a balloon or other means to various levels of the atmosphere and transmitting measurements by radio. It MUST be measured or given to you

• Unlike fixed theoretical rates, the actual ELR changes constantly based on local weather, time of day, radiation, convection, and condensation

Normal Lapse Rate (NLR)

The average rate at which atmospheric temperature decreases with an increase in altitude within the troposphere, averaging about 6.5 °C per 1,000 meters (3.5 °F per 1,000 feet)

• It is a standard baseline or long-term mean representing how fast the air cools as you go higher in the lower atmosphere.

Temperature Inversion

A weather condition where temperature in the troposphere increases with altitude as a layer of warmer air rests on top of a layer of cooler air.

• Inversions are very stable and may last for several days or even weeks

  • Since they are stable, they often trap pollutants and produce unhealthy air conditions in cities

• They form:

  • Over land at night or in winter when the ground is cold. The cold ground cools the air that sits above it, making this lower layer of air denser than the air above it.

  • Near the coast where cold seawater cools the air above it. When that denser air moves inland, it slides beneath the warmer land over the land.

Air pressure

The weight or force of the atmosphere over a unit area

Factors of influence on air pressure include:

1. Number of molecules per unit area

2. The motion of molecules (AKA how excited the molecules are)

3. Size (AKA how the big molecules are)

We talk about air pressure in terms of high pressure (a lot of weight or force) and low pressure (little weight or force).

• At sea-level, you’re going to have high air pressure, and in fact, if you go below sea-level, you’re going to have even higher air pressure

• As you go up in elevation or altitude, the air pressure is going to decrease

Freezing

A phase transition where a liquid turns into a solid as its temperature drops below its freezing point

• Freezing occurs at 0 C° (32 F°)

Night-time auroras

When massive solar storms cause the Van Allen radiation belts (two doughnut-shaped zones of highly charges particles that are located beyond the atmosphere in the ionosphere) to become overloaded with particles, the result is the most spectacular feature of the ionosphere: auroras.

• The particles spiral along magnetic field lines towards the poles

  • The charged particles energize oxygen (O₂) and nitrogen (N₂), causing them to light up.

    • Each gas particle emits a particular color of light

Greenhouse gases

Gases in Earth's atmosphere that trap heat from the sun and keep the planet warm enough to sustain life

Greenhouse gases include: Water (H₂O), Carbon dioxide (CO₂), Methane (CH₄), Nitrous oxide (N₂O), Ozone (O₃), and Chloroflurocarbons (CFCs) and Hydroflurocarbons (HCFC/HFCs)

1. Water (H₂O) as a gas → #1 in abundance

Water is excellent at absorbing longwave radiation

• Humans do not have feasible control over water vapor—the warmer the air, the more energy there is to make water go from a liquid to a gas phase

• Water vapor varies from place to place so it is a highly variable gas

2. Carbon dioxide (CO₂)

Humans are adding more and more CO₂ to the atmosphere through the burning of fossil fuels (coal, oil, gas)

3. Methane (CH₄)

We get methane released throguh the burning of fossil fuels and also when things like permafrost melt

• When compared to CO₂, CH₄ is much stronger—there is just less of it in abundance

4. NItrous oxide (N₂O)

It’s a really powerful greenhouse gas + when compared to CO₂, it is also stronger—there is just much less of N₂O

5. Ozone (O₃)

It has the ability to absorb longwave radiation as well as UV radiation

6. Chloroflurocarbons (CFCs) and Hydroflurocarbons (HCFC/HFCs)

They’re implicated with the destruction of the ozone higher up in the upper atmosphere (in the stratosphere)—specifically the cause for the hole in the ozone layer

Greenhouse Effect

A both natural and accelerated process where certain gases in Earth's atmosphere trap heat from the sun, keeping the planet warm enough to sustain life

• Similar to a greenhouse, shortwave sunlight is allowed to enter through the glass. Then, various objects absorb the heat and radiate longwave radiation. The longwave radiation cannot pass through the gas—instead, it gets trapped and keeps the interior nice and warm

• If we didn’t have the greenhouse effect on Earth, the atmosphere would be below freezing because the longwave radiation would just leave

Influences on Temperature

1. Latitude

The closer you are to the tropical latitude, the warmer it is. The more latitude is increased (AKA the higher up and farther down from the equator you go), the tempature decreases.

2. Altitude

Temperature changes (increasing/decreasing) depending on where you are in the atmosphere (EX: troposphere, stratosphere, mesosphere, and thermosphere)

3. Temporal changes

How temperature changes over time, such as regarding diurnal, seasonal, or annual time periods.

The Annual March of Temperature

The regular cycle of average temperatures rising and falling over the course of a year.

• In a graph showcasing the change in temperature and insolation over the course of 12 months in the Northern hemisphere (mid-latitudes), the following is displayed:

  • Yes, temperature is related to insolation, but it does not occur exactly in tandom with it. Instead, it has temperature lag.

Temperature Lag

The delay between a change in solar input and the corresponding crest or trough in Earth’s surface temperature, caused by thermal inertia from ocean, land, and atmosphere that absorb, retain, and slowly release heat

• It takes a while for the sun’s rays to get to the Earth to warm up and respond with longwave radiation to that temperature (AKA there is a delay)

Thermal inertia

Something’s capacity to absorb retain, and slowly release heat (EX: solar radiation)