WHEN DOES FALL START?
WHEN DOES FALL START?
Are you a successful farmer who has always been making fortunes form your crops, and now you are stressed when the next rainfall will hit the ground? Or are you one of those holiday gurus, always thinking about when to visit your dream beach or mountain hiking, but you are worried about being caught out in the rain? Probably, you there counting days on the calendar asking yourself; when does fall start? 2020 has been full of ups and downs, and everyone thinks when to hit the road and celebrate their long-waited pleasures in the far north or south. You will meet the question from the old-age, probably worried about their new pumpkin spice products filling up their local supermarkets. Others are just sitting on their couches thinking about backyard cookouts, pool parties and picnic weather. Whichever the case, we need to understand that as much as we rejoice whenever summer is knocking on the door, autumn is always the farmers' favourite season. That is why they wish it would last the whole year. But when does fall start or when should they expect the next autumn? That is the question running in their mind after incurring losses due to Covid-19. To help them answer this question, we have to take an in-depth look into the four seasons of the year.
What Is A Season?
Have you heard about Meteorologists and Astronomists? They are dealing with weather and climate changes to give us a clear picture when a season starts and end. Generally, seasons happen the Earth orbits the sun and tilts in its axis at about 23.4 degrees. This causes some parts of the Earth to receive more sunlight than others. However, there are different definitions of a season, depending on which side to take. For instance, Astronomists define a season basing on the position of the Earth while Meteorologists define a season looking at the annual temperature cycles and the calendar. To explain it further, we can define a seasonal start as follows;
Astronomists define seasonal start depending on the position of the Earth on its orbit from the sun. There are two types of season starts; solstice for winter and summer, and equinox for spring and autumn. A solstice start is when the sun is the far southern or northern part of the sky. Equinox is when the sun is on or close to the Earth's equator. The beginning of equinoxes and solstices mark the beginning of new seasons and the end of the previous season. However, during leap years, there are shifts in the solstice and equinox dates, causing a significant change in the seasonal starts. Here are the Astronomical seasons;
- Spring begins on the spring equinox.
- Summer begins on the summer solstice.
- Autumn starts on the autumnal equinox.
- Winter begins on the winter solstice.
According to Meteorologists, the start of each season is defined depending on the annual temperatures and the months of the calendar. Therefore, meteorologist state that a season starts on the first day of the month and lasts for the next three months. However, there are two types of Meteorological seasons as described below;
Northern Meteorological Seasons
In the Northern Hemisphere, every season begins on the first day of the month including the equinoxes and solstices. For instance, spring starts on 1st March and runs up to 31st May, summer begins on 1st June to 31st August, autumn begins on 1st September to 30th November, and winter begins on 1st December to 28th February or 29th in a leap year. This means there are no seasonal changes from year to year, making it easier for farmers to keep a clean record of the weather.
Southern Meteorological Seasons
This is the opposite side of the Northern Hemisphere. This side of the Earth receives the sunlight when the northern part of the Earth is in darkness. Therefore, the changes in seasons in the southern side of the planet are as follows;
- Spring runs from 1st September to 30th November.
- Summer begins on 1st December to 28th or 29th February.
- Autumn runs from 1st March to 31st May.
- Winter starts on 1st June and ends on 31st August.
Does this answer the question; when does fall start? Wait, we need to look at it further.
What Causes the Difference in Seasonal Lengths?
There have been a lot of stories regarding the Earth being hotter currently. Similarly, the Earth has been experiencing more prolonged winters and shorter springs. This means that there have been seasonal shifts which contradict the Meteorological definition of a season. Why? Meteorologists state that all seasons are constant and equal in lengths. Therefore, the difference in lengths and the start of each season forces us to rely on the Astronomical definition. In other words, to know when does fall start, we need to understand the position of the Earth on its orbit in relation to the sun.
The Earth has four seasons caused by the shifts in the sunlight. These seasons are also determined by how the sun rotates the sun and tilting of the axis. This means as the sun circles the sun on its orbit; it causes some of its part to be exposed to the sun while other parts face away from the sun. Although the winter is the shortest season on the planet, sometimes it feels like it will run the whole year. However, the sun does not stay in one position for long. At some point in January, the Earth is closer to the sun (perihelion), while in July, the Earth is farthest from the sun (aphelion). During perihelion, the star's gravitational pull is stronger, causing the Earth to travel faster. Therefore, the Northern Hemisphere experiences shorter autumn and winter. On the other hand, during aphelion, the star's gravitational pull is weaker, causing the Earth to travel slower. This causes the Northern Hemisphere to experience longer spring and summer.
From this observation, it takes less time for the Earth to travel from the autumnal equinox to the vernal equinox, while it takes longer for it to go from vernal equinox to the autumnal equinox. Therefore, the difference in the length of the seasons ranges from 89 days to 94 days in a year. Did you get when to expect the next fall? To understand this better, let us briefly look at each season. The Earth experiences four seasons, starting with spring in the early year to the winter at the end of the year. Although the four seasons are believed to be equal, the Earth experiences variations in the seasonal lengths in different parts of the sphere.
Spring is the first season on the calendar. It starts when the Earth's equator is close to the sun. During spring, the Earth experiences equal day and night, approximately 12 hours each. Additionally, the sun crosses the celestial equator moving northward, rising precisely in the east and sets exactly in the west. Spring occurs a few days to the vernal equinox. So, when was the first spring in 2020?
In 2020, the spring equinox occurred on Thursday 19th March. This goes for those who are always following the Astronomical calendar. It is said that this year's spring equinox came earlier than expected. Why? For the last century, the spring equinox occurred on the 20th or 21st of March. This raises questions if there will be another shift in the next year’s spring equinox. However, we live to see if the changes will occur.
During the summer season, the sun is in the farthest Northern Hemisphere of the Earth. It is characterized by longer days and shorter nights. However, as the Earth starts moving away from the vernal equinox, the length of the days starts to decrease, causing longer nights. 2020 experienced the beginning of summer on Saturday, 20th June. The date marked the official opening of June solstice when the Earth was at the point where the north pole is at its maximum tilt of about 23.5 degrees facing the sun. During this season, the Earth receives most direct sunlight on the northern hemisphere. This brings us to the question; does summer occur the same day?
The occurrence of the summer solstice is not defined based on the specific day or time. It is varied depending on when the sun will reach its farthest northern hemisphere position from the earth' equator. This means that the summer season is likely to occur on 20th, 21st, or 22nd June. During these days, the sun rays hit the Earth at a direct angle, causing efficient or excessive warming. Since the sun is higher in the sky, you will notice your shadow being shorter at noon. However, this is the shortest day of the year for those living in the Southern Hemisphere.
Autumn or Fall
Fall is the third season in the calendar occurring mainly from September. It also appears a few days after the autumnal equinox. During the autumn season, the Earth experiences equal days and nights, approximately 12 hours. This is because the sun rises precisely due east and sets exactly due west as it moves across the Earth's celestial equator southward. When does fall start? In 2020, the autumn season began on Thursday 22nd September. Ideally, autumn starts in the Northern Hemisphere as the spring starts in the Southern Hemisphere. From the Astronomical point of view, the beginning of autumnal equinox is approximated to take place on the same date as the calendar for the next three years. Therefore, if you have been worried about the following fall, you now have the answer. How do you notice the approaching autumn? There are two ways to expect the beginning of fall; Fall weather and Fall foliage.
Winter is when the sun reaches the farthest Southern Hemisphere of the Earth. It is characterized by longer nights and shorter days. As the Earth starts to move closer to the vernal equinox, the amount of sunlight begins to increase, bringing a balance in the lengths of days and nights. Winter is the shortest season of the years, and it crosses to the next years. In 2020, the winter solstice is expected to begin on Monday 21st December. It is the shortest day of the year, with fewest hours of sunlight. Winter Solstice is also the year's important day because the sun is overhead at noon at the latitude called Tropical of Capricorn. The next day, the sun will begin to shift northward.
Why Are There Differences in Seasons in Different Countries?
When trying to define a season, we first look at the countries and regions of the Earth. For instance, countries such as Australia and New Zealand use Meteorological seasons, which means their Spring equinox begins on 1st September every year. Ireland, on the other hand, marks the beginning of spring equinox on the St Brigid's Day, which is 1st February. Moreover, some cultures South Asia divide their calendars into six seasons instead of four seasons. However, Finland, Sweden, and Iceland define season depending on the temperatures and not calendars. Therefore, to understand when does fall start will drive us back to the regions and countries of the Earth.
To find the right answer to the question; when does fall start, we need to have a comprehensive knowledge of the two definitions, the countries, and regional climate. That is, if we use the Meteorological report, the fall season starts on 1st September each year, while the same season began on 22nd September using Astronomical knowledge. However, the dates are bound to change depending on the country and the regional climate. For instance, Iceland celebrates its first day of the summer on the first Thursday after 18th April. This means, estimating the beginning of the fall season will depend on the day the country celebrates its national holiday. On the other hand, Ireland experiences the beginning of spring equinox on 1st February. This brings fall season one or more months before the expected date. Therefore, if you are asking when to celebrate the autumnal equinox, it would be wise if you use autumn indicators such as fall weather and fall foliage.