Seasons: AutumnMadeleine Thomas 11539803Samantha Bennett 11538638

Greek Myth of Seasons: Persephone.Beautiful daughter of Zeus and Demeter; sometimes considered an Olympian. While gathering flowers in a field one day, Persephone was abducted to the Underworld by Hades, who arose in his chariot from a fissure in the ground. Demeter, goddess of the harvest, was heartbroken, and while she wandered the length and breadth of the earth in search of her daughter, the crops withered and it became perpetual winter. At length Hades was persuaded to surrender Persephone for one half of every year, the spring and summer seasons when flowers bloom and the earth bears fruit once more. The half year that Persephone spends in the Underworld as Hades' queen coincides with the barren season. The heroes Peirithous and Theseus attempted to abduct Persephone and bring her back to the land of the living. (Fabianek, 2012)

Early understandings of the seasons:It was initially thought that the seasons were based on Earth being the centre of the universe, with the sun’s orbit around Earth leading to the variant reception of the Sun’s rays.During the 16th Century Nicolai Copernicus proved that the sun was ,infact ,the centre of the universe. Leading to modern understanding of the relationship between the Sun and the Earth and henceforth the seasonal changes.

Why Seasons Change:As Earth orbits the sun its tilted axis always points in the same direction. So throughout the year different parts of Earth receive suns direct rays. The four seasons; Summer, Autumn, Winter and Spring are determined by the relative location of the sun and the location with respect to the constant tilt angle.

Summer:Summer is typically the warmest of the four seasons situated between Spring and Autumn. Summer is signified by the oncoming seasonal characteristics of heat and dry weather with more daylight hours than that of the other seasons. Throughout the year Summer in the Northern hemisphere is traditionally in the months of June, July and August while the Southern Hemisphere experiences Summer in December, January and February.

Autumn:Autumn is consistently cooler than Summer, leading into the Winter season with gradually shorter days. Autumn is known as the season of change with the change of leaf colour, animal behaviours and temperature. Within Northern Countries Autumn is also known as Fall or Harvest. Within the Northern Hemisphere Autumn occurs in September, October and November with the Southern Hemisphere experiencing Autumn in March, April and May.

WinterWinter is typically the coldest season with snow, rain, wind, hail and frost. Winter is often defined by meteorologists to be the three calendar months with the lowest average temperatures. This corresponds to the months of December, January and February in the Northern Hemisphere, and June, July and August in the Southern Hemisphere. Winter experiences the shortest days, with longer nights between Autumn and Spring. During Winter animals such as bears, bats and snakes go into hibernation while birds of colder winter climates migrate toward warmer temperatures.

SpringSpring follows Winter and precedes Summer. When it is Spring in the Northern Hemisphere, it is Autumn in the Southern Hemisphere. Autumn is typified by warmer temperatures with the rejuvenation of plants following Winter creating bright flora displays. Spring experiences gradually longer day lengths leading into the Summer season.

Autumn

Autumn Seasonal ChangesAutumn weather sees the temperature reduce with cloud and rain increasing. Day length reduces with night settling earlier and animals prepare for hibernation. The main visually perceivable change occurring in in the transition from Summer into Autumn is the process of leaf colour change and fall.

WeatherThe weather in Autumn is typically cooler than Summer yet warmer than Winter. The average temperatures in Orange ,New South Wales, Australia for Autumn span from approximately 22.6° as the maximum in March while the minimum is approximately 10.6°, to May where the maximum is approximately 14.2° and the minimum is approximately 4.6°. These months share an average rain fall amount of approximately 61ml a month.

Why the colours change:Three factors influence the Autumn leaf changes; colour-leaf pigments, the length of the night and weather. Within the leaves veins conveys nutrients form the soil and chemicals from photosynthesis, the process in which sunlight is turned into energy within a plant. These veins are responsible for all three colour pigments within the leaf change and the eventual falling of the leaf.

Deciduous TreesDeciduous denotes the "falling off at maturity“ or "tending to fall off“ in regards to plant leaves, and the term is typically used in reference to trees and plants that lose their leaves seasonally, generally during Autumn.

Evergreen Trees (Non deciduous)Evergreen in terms of flora refers to a plant that has continual foliage in all four seasons.

LeavesLeaves contain 3 colour pigments; chlorophyll, carotenoids and anthocynanins. Autumn sees the change of deciduous leaf colouration through the introduction of differentiation of pigment within the leaves creating shades of red, orange and yellow . Following this change leaves often fall and decompose.

Chlorrophyll Is the ever-present chemical, which, when in high concentration, is responsible for the green colouration of leaves. This chemical forms a part of photosynthesis in which sunlight is used to ‘feed’ the plants and henceforth leaves. Upon Autumn shift toward shorter days photosynthesis processes are shortened in response to reduced sunlight and the chlorophyll production is reduced in deciduous trees. As these leaves lose their green, the other colour pigments become visible.

CarotenoidsCarotenoids are another class of colour pigment found within the chloroplast of leaves year round of typically orange, yellow or red colouration. This pigment is not dependent on light, therefore levels are not diminished through shorter days. Carotenoids become visible in response to the diminished influence of chlorophyll in deciduous leaves.

Anthocynanins:Anthocynanins are produced in Autumn in response to the bright light and excess plant sugars in deciduous leaves due to lack of chlorophyll, giving red and purple colouration to foliage. Anthocynanin pigmentation is only visible in Autumn due to its periodic prevalence and the reduced chlorophyll influence on leaf colouration.

Length of the NightExtended periods of darkness indicative of the Autumn and Winter periods reduce the photosynthesis capabilities of the plant, henceforth reducing the chlorophyll production and green pigments within the leaf cells.

Weather impact on leaf changesTemperature and soil moisture influence the colour vibrancy of leaves. Warm, sunny days create the brighter leaf colourings while overcast days and overly cold nights lead to yellow ,orange and brown ldeciduous eaves. A late spring, or a severe summer drought can delay the onset of autumn colour by up to three weeks. A warm period during Autumn will also lower the intensity of autumn colours.

Why the leaves fall:The leaves of deciduous trees fall due to the veins that carry fluids into and out of the leaf, gradually close off as a layer of cells forms at the base of each leaf. These clogged veins trap sugars in the leaf and promote production of Anthocynanins. Once this separation layer is complete and the connecting tissues are sealed off, the leaf is ready to fall. Upon falling leaves decompose, leaving nutrients in the soil.

Autumnal EquinoxThe 24 hour period during the respective Autumn season in which the day and night are approximately equal in length as the spin of Earth on its axis in relation to the sun illuminates equal amounts of light across the Northern Hemisphere.

Day Length:Autumn experiences the gradual shortening of days, with night settling earlier as the seasons lead into the Winter. In response to the earlier night hours Daylight savings was introduced by the Australian; New South Wales, Queensland and Victorian Governments, bringing the clock forward an hour to allow for times to reflect the daytime lighting.

Animal BehavioursAutumn weather indicates to animals such as the Mountain Pygmy Possum in Australia and frogs, snakes, bats and bears from other countries that hibernation season is impending. Animals will alter their behaviours in the Autumn season to eat excessive amounts of food and access large amounts of fluid to build a store to sustain themselves throughout the Winter months of dormancy. Hibernating animal’s metabolic processes slow as they prepare to hibernate. Their heart rate slows, as they maintain their continual drink ing, but will start to eat less. As they prepare to hibernate, animals can rest as much as 22 hours a day in preparation for the impending dormancy.

Celebrations of AutumnMany cultures feature harvest festivals to celebrate the Autumn season including the Thanksgiving holiday of the United States and Canada and the Jewish Sukkot. There are also North American Indian festivals tied to the harvest of seasonally Autumn gathered foods and the Chinese Mid-Autumn ‘Moon festival’.

Autumn is a season of visual appeal with the change of leaf colouration a natural phenomenon in which exhibits characteristics of interest to all ages. The scientific nature of the leaf changes, seasonal weather variation and the alternating day length in respect of season influence reflect a vital element of environmental awareness. The impact of seasons on fauna and their behaviours signifies the overall influence of seasons on day-to-day life.