What do you mean by " sea level "?

Question

ie. above sea level and below sea level.

Answer 1

Sea Level, or mean sea level, the average height, or elevation, of the sea surface. Scientists measure sea level in different locations over a long period of time to eliminate temporary changes in water level due to tides, waves, wind, and air pressure.



Geographers use sea level as the starting level for measuring the height, or elevation, of Earth’s surface. However, over long periods of time and great distances, the level of the sea changes. The science of measuring land features in relation to one another and in relation to sea level is called surveying.



Surveyors have established that the highest location above sea level is 8,850 m (29,035 ft) on the summit of Mount Everest in Nepal, and the lowest depth is 11,033 m (36,198 ft) beneath the Pacific Ocean at the bottom of the Mariana Trench. The lowest elevation on the continents is 408 m (1,340 ft) below sea level at the Dead Sea between Israel and Jordan.





MEASURING SEA LEVEL



The level of the sea is continually changing. In a matter of seconds, a wave can raise and then drop the level of the sea by several meters. In a matter of hours, the tides can also raise or lower the level of the sea, as can changes in air pressure or wind. In order to average out the fluctuations caused by waves, tides, weather, and wind, periodic measurements of sea level over at least 19 years are averaged to determine the mean sea level.



The sea level of a particular place is measured using tide gauges. A tide gauge is a device built to measure water-level variations due to tides and weather and to eliminate effects due to waves. A tide gauge can be as simple as a long ruler nailed to a post on a dock. More sophisticated instruments are usually placed in a stilling well, or pipe, that protects a float connected to a recording device from waves. As tides rise and fall, the float’s motion is recorded.



Sea level can also be measured from space. The TOPEX/Poseidon satellite, launched in 1992, measured sea level and was also used to map the ocean floor. As TOPEX/Poseidon orbited Earth, an altimeter bounced radar signals off the ocean’s surface. The altimeter recorded the time it took for the radar signal to return to the satellite and that gave a precise measurement of the distance between the satellite and the sea surface. Measurement from orbit is the only way to assess sea level independently of land-level changes. TOPEX/Poseidon served as the primary means for monitoring the oceans until it was supplanted by the more accurate sea level monitoring satellite Jason-1, launched in 2001.

Answer 2

What Does Sea Level Mean

Answer 3

Is Mean sea level, sort of average sea level. Sea Level change with Tides so when Ordnance Survey Maps drawn a Mean Sea Level was introduced. This approximately half way between high and low tides and all maps relate to this. Tidal Range at Clevedon in England is 40 feet so this is a significant amount.

Some say sea levels change but there are photographs in Antartica where there is no significant Tidal effect taken by Captain Scotts Party in 1910 approx which show the same sea level on the same rocks as measured in 2000. so sa level rise is no sense.

Answer 4

Mean sea level (MSL) is the average (mean) height of the sea, with reference to a suitable reference surface. Defining the reference level [1], however, involves complex measurement, and accurately determining MSL can prove difficult.



Mean Sea Level as used by military Flight Surgeons and Aerospace Units: Using pressure to measure altitude results in two other types of altitude. True or MSL (mean sea level) is the next best measurement to absolute - and in some ways better. MSL tells you how far you are above an imaginary line at sea level. If you then know the elevation of terrain, the next step is to determine how far you are above ground. It also tells you how thin the air is, which determines your physiological response to that altitude. True Altitude (MSL) has been adjusted for local high or low pressure conditions. FL or Flight Level is another related term that is measured in hundreds of feet. At 18,000 feet, the flight level is one-eight-zero.

Answer 5

If land is level with the sea, then it's called sea level. If it's above the sea, then it's called above sea level...if it's below the sea...I think you know what I'm going say. Isn't it obvious?

Answer 6

Sea level is the average height of the sea. It is used as a reference point when determining altitude.

Example:

If you're on a mountain, you're above sea level.



Note that due to global warming the sea level is rising a few millimetres per year.

Answer 7

Sea level is, of course, the level of the sea.



Mean sea level is the average elevation of the open sea, measured over a complete lunar nodal cycle (18.6 years). On land (or close to land) it is the level surface that would be assumed by water in an imaginary network of frictionless channels connected to the ocean.

Answer 8

Sea level is the level of the ocean. Being above sea level means that you are above the altitude of the ocean; being below sea level means being lower than the alititude of the ocean.

Answer 9

Above sea level is what's not underwater and below sea level is underwater. Ex: Land is above sea level but submarines go below sea level.

Answer 10

...The level at which the sea is. If a city is 20 feet above sea level, it is 20 feet above the sea.

Answer 11

Mean sea level (MSL) is the average (mean) height of the sea, with reference to a suitable reference surface. Defining the reference level , however, involves complex measurement, and accurately determining MSL can prove difficult.

Answer 12

wow...um...yeah...use your head dude.



It's the level that the sea is at.



So if you're 200ft above sea-level..that means you're 200ft above the level of the sea if the sea continued under to the point where you're standing. It's also known as "elevation"

Answer 13

Didn't about 40 years ago, sea level meant being indexed (or measured) from high tide level?

Answer 14

sea-level = the average level of the ocean (between high and low tides)

Answer 15

A topographical distinction used to describe a position above or below "mean" ocean plane.

Answer 16

from the top of the ocean, to the bottom of the sky