Water

The most important substance on Earth is Water and these some of its properties:

Maximum density at 4 °C - 1,000 kg/m3, 1.940 slugs/ft3

Specific Weight at 4 °C - 9.807 kN/m3, 62.43 Lbs./Cu.Ft, 8.33 Lbs./Gal., 0.1337 Cu.Ft./Gal.

Freezing temperature - 0 °C (Official Ice at 0 °C)

Boiling temperature - 100 °C

Latent heat of melting - 334 kJ/kg

Latent heat of evaporation - 2,270 kJ/kg

Critical temperature - 380 °C - 386 °C

Critical pressure - 221.2 bar, 22.1 MPa (MN/m2)

Specific heat water - 4.187 kJ/kgK

Specific heat ice - 2.108 kJ/kgK

Specific heat water vapor - 1.996 kJ/kgK

From: http://www.engineeringtoolbox.com/water-thermal-properties-d_162.html

Always good to site your sources.

What these numbers mean is how you can explain the weather of this planet and how the heat from the Tropics gets transferred to the Arctic.

For the purposes of weather we just need to look at a few of these numbers, the Specific heat and the Latent heat.  

Specific heat refers to the amount of energy one needs to put into or take out of water to change the temperature by one degree Kelvin or Celsius.  And for the record, one adds energy to make it warmer and removes it to make it colder.  So from the number above we see that it takes about twice as much energy to warm a kilo of water than to warm a kilo of ice or water vapour.  To complete the picture if you took a kilo of ice cooled down to -20°C and dropped it into ten kilos of water at 1°C both the ice and the water would be at 0°C when everything evened out.  If one bubbled a kilo of steam at 100°C through fifty kilos liquid water at 0°C, both the steam and the water would be at 1°C afterwards.

Latent heat is the amount of energy that is required to change the state of the substance or in this case water, solid, liquid and gas.  There are two state changes of water naturally on earth, liquid to solid and the reverse, and liquid to  gas and the reverse.  There is a third special kind that happens regularly, sublimation solid to gas and the reverse.

The latent heat of melting is 334 kJ/kg or about eighty times the specific heat of liquid water or over one hundred fifty times the specific heat of ice.  This is energy that must be put into the water to get it to melt or removed to freeze the water.  That is one of the reasons why, if you are in an area where water freezes, it takes water to freeze a long time.  Don't believe me get a thermometer and an ice cube tray.  The water cools to zero relatively quickly and it takes hours for the water to freeze solid.

The latent heat of evaporation is 2,270 kJ/kg or about five hundred and forty times the specific heat of liquid water or over one thousand one hundred times the specific heat of water vapour.  This is the amount of energy that you need to put into water to make it change to gas.  Again with the real world example. Put water in a pot on the stove and put the thermometer in it.  Turn up the heat.  The water starts to boil quickly, all the water is about 100°C, but it does not instantly turn to gas and it won't until the latent cost of turning the liquid to gas.  The energy needs to be removed to turn the vapour to water as well.  

Here is an interesting thought, if you put ice water in a pot and it takes ten minutes to bring it to the boiling point, it would take about fourteen minutes for you to boil the pot dry.

So if you want to melt a kilo of ice at 0°C you could put it in ten kilos of liquid water at 8°C and in the end you will have eleven kilos of water at 0°C .  But, if you  took a little less than seven kilos of ice at 0°C and condensed a kilo of water vapour at 0°C,  you would have eight kilos of liquid water at 0°C.  Rain does not melt snow, it is the condensation that accompanies the rain that melts the snow and ice.

How this applies to weather?  Tropical heat evaporates water, the water vapour is transported elsewhere.  When it rains, the gas turns to water and the air is heated up, warmer air is more turbulent and creates more violent storms. In cooler areas the gas turns to snow and that warms the air up even more.  Some people may have noticed that it rarely snows when it is very cold and the air will warm up if there is a snow storm.  This is simplistic, as warm air holds more water vapour and cold air holds little water vapour so it can not snow a lot unless it is warmer.

Another interesting example of latent heat is a glass of ice tea on a hot and humid summer day.  The ice tea is cold and there is a lot of ice in it.  The ice keeps the ice tea cool but there is a battle of latent heat.  The ice would keep the tea cold longer on a dry summer day than a humid one.  The humid air condenses on the glass the water vapour transfers its energy to the tea through the glass warming the tea the ice in the tea melts taking the heat out of the tea.  Hot humid air has a lot more water vapour than dry air, obviously, so more condensation occurs and the ice melts faster and disappears sooner.

If it was coke or any carbonated beverage, as the liquid gets warmer, the carbon dioxide content drops and the drink becomes flat faster.