Investigation 1
What is Weather ?

Investigation 2
What is Air ? Atmosphere

Investigation 3
Seasons

Investigation 4
Heat Transfer

Investigation 5
Convection

Investigation 6
Humidity

Investigation 7
Clouds
Water Cycle

Investigation 8
Air Pressure and Wind

Investigation 9
Weather and Climate
Hurricane Dean

Careers

Weather Maps

Glossary

Index

In this Science Unit of study, student will learn about the forces that cause our weather. Through experimentation, demonstrations and journal writing, students will discover answers to:

What is Weather?

What causes the Seasons?

What is the Water Cycle?

What is wind and what causes wind?

We will explore:
+ Because of the tilt of the Earth on its axis and the angle the Sun's rays hit the Earth's surface, some parts of the Earth's surface receive more energy from the Sun than other parts.
+ Earth materials heat and cool faster than water.
+ Heat is the kinetic energy of atoms and molecules.
+ Energy moves from one material to another by radiation and conduction.
+ The air above a surface will be warmed or cooled by the surface.
+ Cool air has slower moving molecules that are closer together than warm air. Therefore cool air is denser than warm air.
+ Since warm air is less dense it will rise and will be replaced with cooler air. This is called a convection current
+ Air can hold different amounts of water vapor, depending on the temperature of the air.
+ Water changes from a liquid to a gas by evaporation. During evaporation water absorbs heat from its surroundings causing the water molecules to speed up and the water evaporates. Warmer temperatures or wind will cause evaporation to speed up.
+ Water vapor in air condenses into liquid water when the air temperature cools to the dew point (when the air is saturated)
+ For water to condense to form clouds or rain there must be;

1. moisture (water vapor) in the air
2. cooling temperatures (to reach the dew point)
3. condensation nuclei (a solid surface such as smoke or dust) water vapor to condense on

+ A water molecule might follow many different paths as it travels through the water cycle.
+ Pressure exerted on a gas reduces its volume and increases its density.
+ Differential heating of the Earth's surface by the Sun can create high and low pressure areas.
+ Wind is the movement of air from an area of high pressure to an area of low pressure.
+ Air masses are large bodies of air that are uniform in temperature and humidity.
+ A front is a boundary that separates two air masses.
+ Weather conditions usually change as a front passes by.
+ Climate is the average weather over a long period of time in a region.