AICE MARINE 1.3 Density and Pressure

When a liquid or gas is heated

it becomes less dense

why do liquid or gases become less dense when heated

the molecules move faster, movement

bump each other and spread apart arrangement

Density

is the mass of an object divided by its volume - how much matter an object takes up in a given amount of space

How does density work

Substances with lower density rise

Substances with higher density sink

How does density work in the ocean?

The less dense water rise to surface

Denser water sit lower in the water column

How does density impact marine life?

Because density of ice is lower than sea water, causing ice to float offering a thermal insulator and a habitat for marine organisms;

Changing density of the seawater causes ocean circulation

What factors impact the density of water?

Temperature, salinity, and depth

Temperature is the main

factor that impacts water density

As temperature increases,

density decreases

Warmer H2O sits __ ____ of colder H2O

on top

Thermocline

is between the coldest densest(bottom) H2O layer and the warmest least dense H2O layer where temperature changes drastically.

Tropical waters have a ____ temperature gradient

drastic

Polar waters have a small temperature gradient. Artic waters have small ___

small; thermocline

Temperate waters have ____ temperature gradients

seasonal

Surface mixed layer

the sun heats the surface waters and wave energy carries heat downward

Thermocline

is the layer of rapid temperature decrease where heat energy is quickly lost

Cold layer

is the point where all heat has been lost and everything deeper than that point is constant at about 2C, continuing down to the bottom, regardless of climate at surface

Why doesnt the ocean freeze

1. Salinity 2. Density

As salinity increases

the freezing point of water decreases;

Freshwater 0°C

Saltwater -1.9°C

it is harder to freeze salty water

Density is why the ocean doesnt freeze:

As water freezes the molecules arrange in a crystal lattice making it less dense than liquid water and causing it to float• Due to Hydrogen Bonds

Why is this important?

When ice forms on a body of water, it begins to act as a thermal insulator.reduces the rate of heat lost from the water below itWater below ice is warmer than water exposed to freezing air above itFloating ice is important habitat for many marine organisms including: Polar bears and penguins to hunt from Phytoplankton and algae the basis of the Artic & Antarctic ecosystems Why is this Important?

As salinity increases

the density increases

Fresher less dense water sits

on top of saltier more dense water.

Between the less saline and

the more saline columns of water is the halocline

This means the saltiest water should be in the deep layer EXCEPT.

some layers like tropic seas and polars sea/estuaries

Tropic seas (30° N to 30° S)

have high evaporation & a salty surface layer, but it does not sink because the temperature is so high

Polar seas and Estuaries or areas with increased input of freshwater

will have lower salinities at the surface and increases as you move deeper.

As pressure increases with depth

density increases

Pycnocline

an area of water where the density changes quickly with depth is known

Distinct layers of seawater form

in calm still waters as depth increase

These layers can be mixed by:

• Strong winds•

Wave action•

Storms•

Currents•

Upwelling

Mixing can weaken or break down

thermoclines and haloclines

Stormier weather causes the thermocline to

weaken until it disappears

Density can cause mixing

if the surface waters cools, itsdensity increases, and it sinkscarrying nutrients and gases withit. The water below it rises andmixes with nutrients and gases