What is Weather ?
What is Air ?
Air Pressure and Wind
Weather and Climate
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
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;
- moisture (water vapor)
in the air
- cooling temperatures
(to reach the dew point)
- 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
+ Weather conditions usually change as a front
+ Climate is the average weather over a long
period of time in a region.