Weather Part 2Heating Water and Land

Think About It:

70% of the Earth is water, therefore only 30% is land

Most of that land is cloud covered So most of the incoming solar radiation strikes

water As a result, the interactions between solar

energy and water have a major influence on weather

Absorption by Water

Depends on the state of the water: Snow only absorbs 10% of solar radiation Ice absorbs 50% Liquid water absorbs 93%

But, the ocean’s temperatures do not vary a lot.Because of Specific Heat Capacity.

Specific Heat Capacity

The amount of heat (energy) required to raise the temperature of 1 gram of substance by 1°C.

This is a very large number for liquid water. Water: 4.18Dry air: 1.00Wet mud: 2.51Brick: 0.84

Specific Heat Capacity

The ______ the specific heat capacity, the ______ energy is needed to raise the temperature.

Specific Heat Capacity

The higher the specific heat capacity, the more energy is needed to raise the temperature.

Water is referred to as a heat sink. It absorbs excess heat, without changing state.

Think About It:

1 gram of water needs 21 Joules to raise its temperature by 5 degrees.

1 Joule of energy is the energy require to lift a small apple 1m straight up.

Think About It:

The Sun emits about 3.8 x 1026 Joules each second.

But this energy reaches the entire earth (not just one part), and some is reflected!

Consider This:

Water Balloon’s Heat CapacityWhy doesn’t the water balloon burst?

Consider This:

Back to the beach scenario. Stepping onto the sand feels very hot,

but stepping into the water feels chilly.

Why? Both the sand and the water are exposed to the

same amount of solar radiation. The nature of the substance is why there are

differences in the temperature.

Absorption by Land

Land heats much faster than water

Reasons:

Absorption by Land

1. Water has a large specific heat capacity If 1g of land and 1g of water receive the same

amount of solar energy, the temperature of the land will increase five times more

Absorption by Land

2. Radiation can penetrate a larger depth in water

Radiant energy reaching land will be absorbed in the top few centimeters

Radiant energy reaching water will be absorbed deep into the water

So the energy is spread through the water and not concentrated at the top

Heating Water and Land

Heating soil is conduction: Transfer of heat from the top soil to the lower

soil

Heating water is convection: The movement of water will mix all the water to

make it a uniform temperature

Consider This:

Heating Water and LandWhich warms faster? Which cools faster?

Heating Water and Land

Water heats and cools slowly

Coastal regions have a moderate climate Fewer drastic temperature changes Bodies of water make temperature changes

gradual

Breezes

Sea Breeze: During the dayAir above ground is

warmer than air above water Warm air risesCooler air moves to replace itThe cool air above sinks down

Breezes

Land Breeze: During the nightLand cools faster than

water Air above the sea is

warmerConvection current in

opposite direction