Uneven Heating of Earth’s Surface Earth rotates on an axis (23.5’) So sunlight hits Earth at different angles Creates Climate Zones Tropics Region between Tropic of Cancer (23.5’N) and Tropic of Capricorn (23.5’S) Most direct sunlight Polar Zones Region north of the Arctic Circle (66.5’N) and South of the Antarctic Circle (66.5’S) Least amount of direct sunlight Temperate Zones Latitudes between the Tropics and the Polar Zones Seasonal changes; no extreme heat or cold These climate zones are important and create BIOMES
Wind, Precipitation and Currents Our planet's rotation produces a force on all bodies moving relative to the Earth Due to Earth's approximately spherical shape, this force is greatest at the poles and least at the Equator. "Coriolis effect” the force that causes the direction of winds and ocean currents to be deflected Northern Hemisphere wind and currents deflected toward the right Southern Hemisphere wind and currents deflected to the left.
Climate vs. Weather Weather Day-to-day conditions of Earth's atmosphere precipitation, humidity, temperature, etc. Changes every day Climate The average, year-after-year, conditions (temperature and precipitation) that prevail in a specific region Microclimate Climate in a specific area that varies from the surrounding climate region Ex. The burrow of a Kangaroo rat in the New Mexico desert (dark and cool)
Biomes Terrestrial ecosystems that cover a large region of Earth Characterized by communities of plants and other organisms adapted to the climate and other abiotic factors
Major Terrestrial Biomes Tropical Rainforest Tropical Dry Forest Tropical Savannah Desert Temperate Grasslands (Prairie) Chaparral /shrubland Temperate Deciduous forest North Western Coniferous Boreal Forest/Taiga Tundra
Water The UniversalSolvent
A little bit about water Water is the biological medium on Earth Universal Solvent Solvent: the substance that the solute (salt) is dissovled in (water) Solute: substance (salt) that is dissolved in a liquid Solution: when solutes are uniformly distributed throughout a water solvent All living organisms require water more than any other substance Most cells are surrounded by water, and cells themselves are about 70-95% water The abundance of water is the main reason the Earth is habitable
Water as the Universal Solvent Water is an effective solvent because it readily forms hydrogen bonds When an ionic compound is dissolved in water, each ion is surrounded by a sphere of water molecules, a hydration shell Water can also dissolve compounds made of nonionic polar molecules Even large polar molecules such as proteins can dissolve in water if they have ionic and polar regions
LE 3-7a Lysozyme molecule in a nonaqueous environment.
LE 3-7b Lysozyme molecule in a aqueous environment.
Properties of water
Cohesive and Adhesivebehavior
Versatility as a solvent
Transpiration: Evaporation of water through the leaves of plants “stomata” are the tiny pores in the leaves of plants through which water escapes
Cohesive and Adhesivebehavior
Cohesion: whensimilarmolecules stick together (droplet of water)
hydrogen bonds hold water molecules together
Cohesion helps the transport of water against gravity in plants
Adhesion: whenunlikemolecules stick together (water on glass)
Adhesion of water to plant cell walls also helps to counter gravity
How does water getfromroots to the leaves of a talltree?
Cohesion accounts for SURFACE TENSION Surface tension is a measure of how hard it is to break the surface of a liquid
Moderation of Temperature Water absorbs heat from warmer air and releases stored heat to cooler air Water can absorb or release a large amount of heat with only a slight change in its own temperature
Weather and Water Coastal Areas During the hot day, the ocean/lake will absorb energy from the air so that it feels cooler At night, when the air is cooler, the water releases all the stored energy, making it warmer at night “moderate” temperature Inland areas (no water nearby) During the hot day, there is NO water to absorb heat so it is realllllyy hot (think desert) At night, no energy is release, so it gets very cold
Heat and Temperature Kinetic energy is the energy of motion
Heat is a measure of the total amount of kinetic energy due to molecular motion
Temperature measures the intensity of heat due to the average kinetic energy of molecules
Water’s High Specific Heat The specific heat of a substance is the amount of heat that must be absorbed or lost for 1 gram of that substance to change its temperature by 1ºC Water’s high specific heat minimizes temperature fluctuations to within limits that permit life Heat is absorbed when hydrogen bonds break Heat is released when hydrogen bonds form
Evaporative Cooling Evaporation is transformation of a substance from liquid to gas Heat of vaporization is the heat a liquid must absorb for 1 gram to be converted to gas As a liquid evaporates, its remaining surface cools, a process called evaporative cooling Evaporative cooling of water helps stabilize temperatures in organisms and bodies of water “Sweating” liquid to gas requires heat…this heat comes from inside our body What does the saying “It’s not the heat, it’s the humidity” mean? Humidity: water vapor in the air If there is more water in the air, it is harder for water molecules to evaporate off your skin…so how do you feel? Hot and sticky!