Earth's Climate and Global Patterns

Earth's Climate

• Climate constitutes the long-term weather conditions of an area.
• Temperature, precipitation, sunlight, and wind are the four main abiotic climate components.
• Abiotic factors determine species abundance, types, and distribution on Earth.
• Macroclimate involves climate patterns on a large scale.

Global Climate Patterns

• Solar energy and Earth's movement determine global climate patterns.
• The warming effect of the sun causes temperature variations driving air and water circulation.

Latitudinal Variation in Sunlight Intensity

• Sunlight intensity varies latitudinally.
• Sunlight strikes the Earth directly at the equator and at low angles near the poles.
• The sun is overhead at the equinoxes.
• The Earth's atmosphere affects the intensity of sunlight.
• Key latitudes include 90°N (North Pole), 60°N, 30°N, 23.5°N (Tropic of Cancer), 0° (Equator), 23.5°S (Tropic of Capricorn), 30°S, 60°S, and 90°S (South Pole).

Global Air Circulation and Precipitation Patterns

• Rising air masses release water, causing high precipitation, notably in the tropics.
• Dry, descending air masses lead to arid climates, particularly around 30° north and south.
• Cooling trade winds blow from east to west in the tropics, while prevailing westerlies blow west to east in temperate zones.
• Key latitudes include 66.5°N (Arctic Circle), 60°N, 30°N, 0°, 30°S, 60°S
• An arid zone is located around 30°N.

Regional and Local Effects on Climate

• Climate is affected by seasonality, large bodies of water, and presence of mountains.

Seasonality

• Seasonality at high latitudes is due to Earth's axial tilt and its orbit around the sun.
• Belts of wet and dry air around the equator shift throughout the year, causing winds to shift as well.
• Key dates include the March equinox, June solstice, September equinox, and December solstice.
• Earth has a constant tilt of 23.5°.

Bodies of Water Influence Regional Climates

• Air rises over warm land and pulls a cool breeze from the water across the land during the day.
• At night, air rises over warmer water and carries the cooler air from land back over the water; the process is then replaced by warm air from offshore.
• Ocean currents influence regional climates

Mountains

• Rising air releases moisture creating a rain shadow and absorbing moisture on the leeward side.
• Mountain ranges affect the amount of sunlight that reaches an area.
• South-facing slopes get more sunlight than north-facing slopes in the Northern Hemisphere.
• Temperature drops about 6°C for every 1,000 m increase in elevation.

Microclimate

• Microclimate is determined by the differences in the environment that affect light and wind patterns on a fine scale.
• Every environment has differences in abiotic factors like temperature, light, water, and nutrients and biotic factors like other organisms.

Biomes Distribution

• Biomes are life zones with a vegetation type (terrestrial) or a physical environment (aquatic).
• Climate is essential for where terrestrial biomes are located.

Terrestrial biomes

• Terrestrial biomes are named for physical, climatic factors and vegetation.
• Terrestrial biomes mix into each other through wide or narrow ecotones.
• Types of terrestrial biomes include Tropical Forest, Savanna, Desert, Chaparral, Temperate Grassland, Temperate Broadleaf Forest, Northern Coniferous Forest, Tundra, High Mountains, and Polar Ice.

Important feature of terrestrial biomes

• Vertical layering in forests may consist of upper canopy, low-tree layer, shrub understory, ground layer of herbaceous plants, forest floor, and root layer.

Convergent Evolution

• Similar traits arise in distant biomes through convergent evolution.
• Cacti in North America and euphorbs in African deserts appear similar but are from different evolutionary lineages.

Disturbance

• Disturbance is an event like a storm, fire, or human activity that changes a community.
• For instance, recurring fires can eliminate woody plants and maintain savanna vegetation.

Describing Terrestrial Biomes

• Terrestrial biomes contain distribution, precipitation, temperature, plants, and animals.

Tropical Forest

• Tropical forests are distributed in equatorial and subequatorial regions.
• Rainfall is constant in tropical rain forests but seasonal in tropical dry forests.
• Temperatures here are hot year round at 25–29°C.
• There is a layered vegetation with intense light competition.

Temperate Broadleaf Forest

• These are at midlatitudes in the Northern Hemisphere, with smaller areas in Chile, South Africa, Australia, and New Zealand
• Significant precipitation falls during all seasons. Winters average 0°C, and summers are hot and humid reaching near 35°C.
• Vertical layers are dominated by deciduous trees in the Northern Hemisphere and evergreen eucalyptus in Australia.

Desert Biome

• Deserts occur in bands near 30° north and south of the equator, and in the interior of continents.
• Precipitation is scarce and inconsistent, generally less than 30 cm yearly.
• Deserts may be either hot or cold.

Temperate Grassland

• These are found on many continents.
• Winters are cold, often below –10°C, and dry; summers are hot, often near 30°C, and wet.
• Grasses and forbs are the dominant plants and adapted to fire and droughts.
• Native animals include grazers such as bison and wild horses and small burrowers like prairie dogs.
• Most grasslands have been converted to farmland.

Aquatic Biomes

• Aquatic biomes account for the biosphere's largest part.

Marine and Freshwater Biomes

• Marine biomes contain salt concentrations of about 3%.
• Oceans cover about 75% of Earth’s surface impacting the biosphere greatly.
• Freshwater biomes contain salt concentrations of less than 0.1%.
• Freshwater biomes are closely linked to soils and the biotic components in the surrounding terrestrial biome.

Zonation in Aquatic Biomes

• Aquatic biomes have zones that are classified by light penetration, temperature, and depth.
• Marine zones are categorized into intertidal, neritic, and oceanic zones.
• Key zones in lakes include the littoral and limnetic zones.
• Common zones include photic, aphotic, benthic, and pelagic zones, as well as the abyssal zone in marine biomes.

Temperature Boundary

• A temperature boundary known as the thermocline divides the warm upper layer from the cold deeper water in oceans and most lakes.
• Many lakes undergo turnover.

Describing Aquatic Biomes

• The distribution of freshwater lakes include temperate, tropical lowland, oligotrophic and eutrophic categories.
• Major aquatic biomes are defined by their environment, chemical environment, geological features, photosynthetic organisms, and heterotrophs.
• Temperate lakes have seasonal thermoclines, while tropical lowland lakes have a year-round thermocline.
• Oligotrophic lakes are generally deep and have low nutrients and high oxygen.
• Eutrophic lakes are generally shallow and are nutrient-rich and often depleted of oxygen.

Zooplankton and Invertebrates

• Zooplankton are drifting heterotrophs that graze on phytoplankton.
• Invertebrates stay in the benthic zone, but fishes can live in all zones where there is enough oxygen.

Streams and Rivers

• Headwaters are generally cold, clear, turbulent, swift, oxygen-rich, and narrow.
• Downstream waters form rivers and are generally are warmer, more turbid, wider, and less oxygenated, with silty bottoms.
• They may contain phytoplankton and rooted aquatic plants.
• A diversity of fishes and invertebrates reside in undisturbed rivers and streams.

Estuaries

• An estuary is a transition area between river and sea and are nutrient-rich and highly productive.
• Salinity varies with differing tides.
• They contain channels, islands, natural levees, mudflats, and grasses.
• They create abundant food and attract marine mammals, fish, waterfowl, and marine invertebrates.

Marine Benthic Zone

• The marine benthic zone is the seafloor below surface waters.
• The zone is comprised of coastal, neritic, and offshore pelagic zones.
• Organisms in the very deep benthic (abyssal) zone have adaptations to persistent cold and extremely high water pressure.
• Soft sediments dominate the substrate, with some areas being rocky.
• Chemoautotrophic bacteria is the basis of the food chain here.

Species Distribution

• Species distributions result from ecological and evolutionary interactions through time.
• Ecological time is the time frame of interactions between organisms and the environment.
• Evolutionary time is over many generations and captures adaptation through natural selection.

Ecologists Ask Questions About Species

• Ecologists ask questions about where species occur and why species occur

Factors Influencing Species Distribution

• Both biotic and abiotic factors play a role in influencing species distribution.
• Factors to consider concerning why a species distribution is either expanding or being reduced: dispersal, habit selection, biotic factors, and abiotic factors.

Dispersal

• Dispersal moves individuals away from high-population centers or the origin area.
• Dispersal contributes to the global distribution of organisms

Natural Range Expansions

• Natural range expansions show the effect dispersal has on species distribution.
• Cattle egrets began populating the Americas in the late 1800s and have expanded their distribution.

Global Climate Change

• Climate changes can greatly affect the biosphere.
• Prediction on the effects of climate change can be forecasted by observations of the past.
• Tree distribution patterns changed after glaciers retreated 16,000 years ago.
• Species that cannot disperse easily may have limited ranges or face extinction as climate changes.

Species Translocations

• Species translocations involve organisms intentionally or accidentally moved from their original distribution.
• A successful transplant show that the species potential range is greater than current one.

Habitat Selection Behavior in Response to Factors

• Species distribution is limited by habitat selection responding to biotic and abiotic factors.

Abiotic Factors

• Abiotic factors affecting distribution are temperature, water, sunlight, wind, as well as rocks and soil.
• Most abiotic factors can fluctuate across space and time.