[Music] this video talks about deep ocean currents in the last video we talked about shallower Asian currents that were driven by winds blowing over the water the deep ocean doesn't feel the wind and so deep ocean currents are driven by differences in water density which are directly related to variations in temperature and salinity in the ocean this image should look familiar from our discussion of ocean salinity let's look at it again to get an idea of the places that are saltiest in the ocean take a moment to review what we talked about in the past also think about the places in the ocean that are the coldest and the warmest high-density occurs in the ocean where the water is the coldest and the saltiest this is where water sinks and it turns out that sinking water is what drives our deep ocean circulation the two places that have the densest water are near Antarctica and near Greenland both of these places are extremely cold and they also are salty the Antarctic bottom water is salty because this is a place where a lot of ice is forming this water is the deepest and the most dense on the planet it's the deepest because it is the most dense the North Atlantic deep water near Greenland is salty because of cooling and evaporation this is the most prolific deepwater on the planet the most of volume of water but it's not quite as dense as the Antarctic bottom water this diagram shows our thermohaline circulation which is our circulation based on temperature and set thermo is temperature hey Linus salt temperature and salt drive a density current where at locations 1 & 2 were our deep water forms ocean water sinks all the way from the surface of the ocean down to the bottom of the ocean then it's first to move along different paths throughout the ocean until it gradually Rises and diffuses back up toward the surface of the ocean gradually warming as it rises the sinking of the deep water happens only at a few places on the globe that's right these two places drive the entire ocean conveyor belt as it is called if we look at it from a side view we see we have the Atlantic Ocean in this depiction with North on the left and south on the right so a Greenland is going to be on the left side of our diagram and Antarctica is on the right side called water near Greenland sinks forming our North Atlantic deep water cold water near Antarctica sinks forming our Antarctic bottom water as we previously discussed Antarctic bottom water is the densest water on the planet therefore it layers on the bottom of the Atlantic Ocean the next densest water is our North Atlantic deep water which forms near Greenland so that is the next layer moving up in the Atlantic Ocean we have some intermediate water that also forms and then all the way on the top we seem our warm tropical surface water this matter is very warm and therefore easily floats on top above the picnic line as we discussed in video 2 of this segment the circulation through our deep oceans happens very slowly at an average rate of point zero three two point zero six kilometers per hour if we compare this to the Gulf Stream the Gulf Stream was three kilometers per hour therefore our deep ocean currents are a hundred times slower than our service ocean currents this means that from the moment the water sinks in deep water formation until the moment it rises back to the surface it takes hundreds of years therefore properties of our deep ocean water do not mix with the atmosphere and are very isolated from the rest of the ocean