Science Fundamentals: Method, Measurement, Weather
Scientific Method Basics
Q, R, H, E, D, C, P
Aristotle gave us the hypothesis step (if you think hard enough, you can figure out the answer).
Galileo gave us the experiment step 2,000 years later.
For a controlled experiment, only one variable can change. If more than one changes, then the results are invalid.
Scientific Measuring Tools
Know the scientific measuring tools and what they measure:
- Metric ruler: measures length in centimeters
- Thermometer: measures the temperature of objects
- Triple Beam Balance: measures mass (in grams)
- Microscope: allows us to see objects we can’t with just our eyes (magnifies objects)
- Spring Scale: measures weight (the pull of gravity on an object)
- Beaker: measures the volume of liquids (in milliliters)
- Graduated cylinder: measures the volume of liquids (in milliliters)
Reading Measurements
Know the definition of meniscus and how to properly read the measurement in a graduated cylinder.
Know how to write “cubic centimeter”: cm³ which means each side of the cube is one centimeter in length.
Know how to measure the volume of an irregularly shaped object using displacement.
Density
Density is calculated as:
Density = Mass / Volume
If given the mass and volume, calculate the density of an object.
The density of water is 1 g/cm³.
The volume of a rectangular object is calculated as: Length x Width x Height.
The instrument that measures mass is a triple beam balance.
Objects that are less dense float in substances that are more dense.
Salt water is more dense than fresh water.
Weather Phenomena
Tornadoes
Strong thunderstorms can produce tornadoes.
There is an area in the United States where thunderstorms often produce tornadoes; it’s called Tornado Alley and is located north of Texas.
Tornadoes are measured on a scale of 0-5 called the Fujita Scale based on the strength of the wind.
Air Pressure
Air has pressure. Air pressure is measured with an instrument called a barometer.
The Sun is the major source of energy for circulating the atmosphere and oceans.
Weather Factors
Weather is the result of short-term variations in:
- Temperature
- Humidity (how much water vapor is in the air)
- Air pressure
Pressure Systems and Clouds
High pressure does not allow air to rise, so clouds don’t form.
Low pressure allows air to rise. When the air reaches its dew point, clouds form. Precipitation is usually associated with low pressure systems.
Precipitation Types
- Rain: happens when both the upper air is warm and the air near the ground is warm.
- Sleet: happens when the upper air is warm and the air near the ground is cold. The raindrops freeze.
- Snow: happens when the upper air is cold and the air near the ground is cold.
Global Winds and Air Masses
Global Wind Formation
Global winds are created when the Sun unevenly heats the Earth. The air above the warm ground is warmed. Warm air rises. Away from its heat source, the air cools and sinks. This creates wind. Because the Earth is rotating, the wind appears to bend, giving us global wind patterns.
The global wind pattern over the United States is Prevailing Westerlies.
Air Masses and Fronts
The global winds move the air masses in the atmosphere. Air masses that are formed over water have lots of moisture. Air masses formed over land are typically dry. The air masses crash together to create cold and warm fronts.
Know the clouds and weather associated with a cold front and a warm front. Know how the two air masses come together:
- Cold front: cold air slams into warm air.
- Warm front: warm air slides up and over cold air.
Water Cycle and Heat Energy
The water cycle moves heat energy from the ocean into the atmosphere.
When you add heat energy, particles move more rapidly and expand (move apart).