WEEK 1: Introduction

• Water (H2O) simultaneously exists in 3 states: Liquid, Solid, & Vapor. • Environment: defined by the physical and biotic elements present at a site. (Controlled by factors such as climate, topography, and biology). • Topography: arrangement of the environmental features of an environment.

• Glacial environmental (polar climate) → Antarctic mountains have clear cut off from snow coatings. • Desert environment (arid climate) → Death Valley is surrounded by big mountains that stop the sea from coating the sealevel land with water. • Rainforest environment (tropical climate) → Wet climate, dense with plants and animals. Sandwiched between the Glacial and the desert environments on the equator. • Mountainous environments (highland climate) → Himalaya’s are the tallest mountains, it gives them a distinct climate. As you gain elevation, you lose temperature. Look at Tanzania, 3° from the equator; and yet there are ice glaciers on the equator because they’re located on mountains. (Mountains don’t just form anywhere!)

Freshwater aquatic settings: • • Fluvial (river) environment → When located on mountains, velocity of water increases. Harder for animals to live in them. • Lacustrine (lake) environment → Not as turbulent the further lowland you go. More appealing to animals. Brackishwater aquatic settings: • Marginal Marine (deltaic environment) → A transitional setting formed where a river enters a standing body of water like a sea or lake, e.g. Mississippi delta. Saltwater aquatic settings: • Benthic Marine (shelf) environment → The biologically rich seafloor bottom extending from the shoreline to the edge of the continental shelf. Organisms such as corals must be a part of the environment for coral reefs to be produced. Yes the climate has to be right, but so does biology. You can’t have coral reefs without corals building those reefs. • Benthic Marine (abyssal) environment → Deepest part of the aquatic environment, yet we still have lots of living things that have adapted to it.

Physical factors (terrestrial settings): - Temperature. - Precipitation. Physical factors (aquatic settings): - Water temperature. - Salinity. - Water depth. - Pressure. - Light availability. - Water turbulence. - Physical disturbance. - Water clarity → Turbulent water can make water look murky or cloudy. Not many animals or plants can live in that environment. But when it’s clear, you can have a lot of photosynthesis go on. Biological factors (terrestrial and aquatic settings): - Biogeochemistry. - Ecosystem engineering → When organisms build onto their environments, like coral reefs.

Terrestrial settings: - Temperature. - Precipitation. Aquatic settings: - Water temperature. - Salinity (evaporation rate; precipitation).

Latitude • Temperature gradient primarily driven by pattern of energy input from Sun → How far North or South you are from the equator, temperature gradient. Atmosphere • Atmospheric circulation, cloud cover, precipitation → Shuffles heat around over the surface of the earth. Determines where precipitation happens. Oceans • Oceanic circulation, land-water heating differences → Circulate sea water in particular directions, redistributes heat. Water heats up differently from dry land. Surface topography • Altitude influences temperature and precipitation → The further high up you get, the colder it gets. Determines whether you’re on dry land or underwater.

• Temperature (altitude) • Precipitation (altitude; rainshadow effect).

• Water depth. • Water turbulence (depth; gradient or slope).

Plate tectonics. • Location of continents versus ocean basins. • Distribution of mountain chains and volcanoes.

Factors influencing environments can vary on many timescales. • Hours (weather; day/night; high/low tides). • Weeks to months (spring/neap tides; seasons). • Decades to thousands of years (ecological successions). • Tens of thousands to millions of years (orbital parameters; glacial cycles; continental drift; biological evolution).

Important ways of conceptualizing how to think about things Identify the Question ↓ Gather data (make observations, measurements) ↓ Form a hypothesis (suggested solutions) ↓ Make predictions (if hypothesis is correct, then…) ↓ Test the hypothesis (do new data fit the predictions?) ↓ “Yes” (Hypothesis is supported; might be a general theory) OR “No” (hypothesis is wrong, so reject it)

In common usage, a theory is an idea that is intended to explain facts. • Hypothesis; guess; postulation; speculation; conjecture; unproved assumption; belief. • A scientific theory has validated explanatory power. - Extensively tested hypothesis; has not been falsified by experiment or observation. - A general principle that is supported by empirical data.

• Atomic theory (matter is composed of discrete units called atoms). • Cell theory (living organisms are composed of one or more cells; cells come from pre-existing cells by division, etc.). • Theory of plate tectonics (explains many of Earth’s surface features; see Lecture 5). • Theory of evolution (descent with modification; survival of the fittest, etc.).

Earth’s surface temperature and climate is determined by incoming energy from the Sun (insolation). - Essentially none of the heat within the earth affects the surface. It’s instead determined by the Sun.

• The Sun is the only object in the solar system with sufficient mass to sustain nuclear reaction and produce radiant energy.

• Conduction • Convection • Radiation

• Molecule-to-molecule transfer of heat energy as it diffuses through a material. - Vibrations of molecules cause collisions that move neighboring molecules. • Net heat flow from area of higher temperature to one of lower temperature. • Rate of heat flow depends on conductivity of material. - E.g., land is better heat conductor than air. - [Diffusion of the heat THROUGH the object]

• Vertical and/or lateral motion of the heated medium. - Medium must flow, so it only operates in liquids and gases. - Warm.. - Cooler.. • [water at bottom of pan gets hotter, therefore wanting to rise to the top where it will lose its heat and lose its density and sink back down] / “convection cells” / ONLY works in fluids (liquids and gases). Solids do not flow.

• Energy in the form of waves or particles. - Electromagnetic radiation. - Particle radiation. - Acoustic radiation. - Gravitational radiation. • Travels through space or material medium → The only way energy can be transferred through the sun to other planets, through the vacuum of space!

• Solar radiation travels to Earth as electromagnetic waves of various wavelengths (energies). • Hotter objects emit shorter wavelength radiation. • The Suns’s surface is c. 6000°C, and emits shortwave radiation: - 8% UV, X-Ray, and gamma ray. - 47% visible light. - 45% infrared wavelength. • Earth’s surface is 15° C, and emits mostly longwave (infrared) radiation. - You could see the Earth from space if you had an infrared camera, because the Earth would be glowing from the heat.

• The more energetic something is, the shorter the wavelength it emits.

second section - Solar radiation that reaches Earth’s atmosphere and surface is called insolation. - The solar constant is the average amount of insolation that reaches the top of Earth’s atmosphere (= thermopause;.. - Solar.. - 1 watt… - 1 joule.. - Big # means an awful lot of energy coming from the sun. If you took a cup of water at this number above earth’s surface, it would boil instantly → If all this energy would hit the earth, all the water would boil. This is where the atmosphere comes in.

• Not all the incoming solar radiation at the thermopause reaches Earth’s surface. - Must pass through the atmosphere first. - Subject to reflection, scattering, and absorption.

• Without atmosphere, Earth would be like Mars, which has lost its atmosphere. - About 31% of incoming solar radiation is reflected or scattered back out to space without being absorbed. - 21% reflected off clouds. - 3% reflected off Earth’s surface. - 7% redirected back out to space by atmospheric scattering.