We live in a world of constant change where energy flows, and nothing remains exactly the same. This flow of energy can be seen in all aspects of our lives but is perfectly represented by the phenomenal ebb and flow of the ocean’s tides, where water moves and new ocean habitats are exposed.
Throughout this article, we are going to dive deep into the components that create the differences between high vs low tide, their causes, how the movements affect local ecology, and the overall characteristics of these ocean movements.
Credit: Linnaea Mallette (left) & NPS (right)
Main Differences Between High Tide vs Low Tide
- Water Level: High tides result in an increased level of water, while low tides result in coastal water levels reaching their lowest point
- Moon position and Luna cycle: High tides occur in areas where the moon is closest to the earth, as well as on the opposite side of the earth; low tides occur in areas parallel to the moon
- Coastal regions: Low tides expose larger areas of coastal regions, while high tides over these intertidal zones with water
- Timing: Most places experience two tides a day, with high and low tides occurring approximately 6 hours and 12.5 minutes apart
- Wave action: High tides result in more water in coastal regions which causes larger, more powerful waves. Low tide waves are small are break further away from the shoreline
High Tide
When the water level of a particular tidal cycle reaches its highest point, it is referred to as high tide. This level not only differs according to geographical location but is also directly affected by the moon cycle. This means that high tide will occur at different times, as well as reach a different maximum level. At high tide, a shoreline experiences its greatest influx of water.
What Causes High Tide?
High tides are primarily caused by the gravitational interactions between our planet, the moon, and the sun. As the moon is the closest gravitational influence to Earth, it has a greater effect on our tides than the sun. However, they both remain relevant.
As the moon’s gravitational force pulls on the earth, less dense material like ocean water is pulled towards the moon, which causes a bulge in the ocean.
Although, when compared to the entire earth, this bulge is hardly noticeable, for smaller creatures such as ourselves, we notice a rising in sea level. In this sense, it could be said that high tides follow the moon.
Simultaneously with this high tide created from the moon, another, yet smaller, high tide is formed on the opposite end of the earth. This is referred to as the opposite bulge, which is maintained by inertia.
The Characteristics of High Tide
Although we know high tide results in a higher water level, it’s important to grasp the characteristics of high tide in order to get a full understanding.
Water Level
High tide is typically characterized by the rise of water levels (this can occur in the ocean or lakes and other large bodies of water. This rise in water levels is directly related to the distance between the moon and the earth, the geographical location of the observed tide, the tidal range, the coastal area, and the depth of the local ocean floor.
Timing Of High Tide
There are typically two high tides per day. However, this is not an exact number as the tides are influenced more by the moon’s cycle than that of the sun. A lunar day is approximately 24 hours and 50 minutes long, which is why there are not always two high tides in a single sun cycle.
A typical high tide cycle, therefore, lasts approximately 12 hours and 25 minutes, although this is also affected by the gravitational pull of the moon, local typography, and geographical location, which means the timing of a high tide will differ from region to region.
Tidal Range
The tidal range refers to the difference in water levels between high and low tide. When the water level is at its largest range for the particular cycle, it is referred to as high tide. Once again, this range will vary on different factors, such as the proximity of the moon to the earth and the location of the tide.
For example, during a full moon, when the moon is at its closest to the Earth, a larger tidal range will be experienced. Similarly, when the coastal ocean floor is shallow, the tides represent a larger difference between high and low.
Wave Action
High tides bring more energy to waves, which results in larger, more powerful wave action. As the water level rises, waves can travel closer to shore, which results in an increased peak, and breaks closer to the coastline.
This added energy could result in the changing of coastal regions by creating erosion, shifting sand banks, and moving rocks along the shoreline.
Relation To The Moon
The closer the moon is to the Earth, the larger the gravitational pull. This means that during times such as a full moon, when the moon is at its closest, the ocean levels will experience the largest pull, and therefore, a higher high tide will be experienced.
When the moon and sun are in line with the earth (new or full moon), the maximum tide difference will be experienced. This is known as a spring tide.
Low Tide
Low tide, similar to high tide, is directly affected by the moon’s position on the earth; however, unlike high tide, low tides occur in areas of the earth with the least gravitational pull. Low tides occur at the same times as high tides, however, in different places on the globe. The easiest way to understand this is by looking at the earth in terms of compass points. If there is a high tide on the North and South points, then a low tide will be experienced on the east and west points.
What Causes Low Tide?
Similar to high tides, low tides are created by the gravitational pull from the moon. However, low tides are an indirect result of this force. When water is pulled towards two sides of the earth (forming high tides), the result on the parallel sides of the earth is a decrease in water volume.
One way of looking at this is that for there to be an increase in water on two sides of the earth, the water needs to come from somewhere. This results in less ocean water on parallel sides to the moon and, therefore, a lower tide.
Low tides are directly proportional to high tides. This means that during a high tide, there will also be a low tide. Oppositely, during neap tides, the difference between high and low tides will be smaller yet still proportionate.
That said, it’s important to remember that factors such as moon proximity and geography impact low tides as they do with high tides.
The Characteristics of Low Tide
Once you understand how high tides work, it’s a lot easier to understand low tides, as they behave in a similar yet opposite manner.
Water Level
Low tide is typically characterized by a decrease in water levels. This decrease will differ according to geographical location, the moon cycle, and coastal typography but will always result in a decrease in water level which exposes the intertidal zone and extends the coastline.
Timing Of Low Tide
Similarly to high tides, low tides occur approximately twice a day following the lunar cycle. There will always be a low tide in response to a high tide, and the tide’s size will be equal, opposite to that of the high tide.
That said, although the change in water level is the same, it may result in a different tidal range, depending on the specific location.
Tidal Range
In areas with a big tidal range, low tide can expose large amounts of the ocean floor, which results in a significant increase in coastal regions. As with high tide, this range will differ according to the moon cycle, as well as the location. Some tidal ranges are very small, which results in a minimal difference between low and high tides.
Intertidal Zones
The intertidal zone is the area between the high tide and low tide marks which is exposed during low tide.
When this area is clear of water, it exposes the diverse number of marine species such as mussels, crabs, barnacles, seaweed, and various other life that can often be found in tidal pools to oxygen and sunlight, which allows for better survival and adaptations.
Relation To The Moon
When the moon is closest to the earth, we experience the largest change in tides. As full and new moons result in spring tides, this increases the high tide level while simultaneously decreasing the low tide level.
During times when the sun and moon are at a right angle to each other, there is less gravitational pull, which results in a higher low tide, as well as a lower high tide.
FAQs
Are high and low tides the same as ocean currents?
Although tides and ocean currents both refer to the movement of water, they are not the same. Tides refer to the increase or decrease in water height, while currents refer to the movement of water in a left-to-right, or back-and-forth motion
What is the biggest tidal range of high tide vs low tide?
The Bay of Fundy, found between New Brunswick and Nova Scotia, has the highest tidal range in the world, with water levels changing up to 53 ft (16.3m) during spring tides.
Does everywhere on Earth experience two high and low tides per day?
Although most places on Earth experience four times a day (2 high and two low), this is not the case everywhere. Some places, such as the Gulf of Mexico, have diurnal tides, meaning they only experience a single high and single low tide per lunar day.
Can we predict the timing of high tide vs low tide?
Yes, it’s possible to predict the tides of a particular location by making use of a tide chart and or Luna calendar. These charts take into account the position of the Earth, moon, and sun, as well as geographical location.
That said, because typography affects tide highs, these charts are not always 100% accurate and should be used more as a guideline.
