# Relationship between density and weather

air density is the sum of the gases present. The partial Weather · Physics. What is the relation between air density and humidity (mathematical terms)?. Understanding air density and its effects By Jack Williams, posavski-obzor.info In simple Altitude and weather systems can change the air's pressure. . you can read an article I did for the Aircraft Owners and Pilots Association's Flight Training . [1] The correlation between the electron temperature (Te) and electron density (N e) at km height at magnetic dip latitudes (MLat) less than.

Making a connection between laboratory scale observations and atmosphere-scale data sets. Drawing on hands-on observations to explain an aspect of a natural system. Thinking about a phenomenon density of air that is invisible. Imagining boundaries or limits, and thinking about phenomena within those boundaries a column of air, a parcel of air Linking properties that are detectable to the human senses e. Linking properties that are measurable at the macroscopic scale e.

Building a chain of reasoning from cause to effect.

Building a chain of reasoning from observation to interpretation. Using time series graphs; comparing how different parameters vary through time. Recognizing that a measurable property varies through time barometric pressure rises and falls as weather systems pass and also through space barometric pressure decreases with increasing elevation. Using a scatterplot; thinking about two or three data parameters simultaneously. Make a Barometer Students create home made barometers and discuss how they work.

Instructions for this activity are contained in many middle school science books. Torricelli's discovery of air pressure Students view and discuss the section of the "Connections" video in which Torricelli's discovery of air pressure is illustrated. In this video, a mercury barometer is carried up a mountainside, and the mercury is seen to fall as the climber ascends. The interpretation is that the weight of the mercury balances the weight of the overlying air.

The weight of the overlying air decreases as the climber rises higher in the atmosphere; thus less weight of mercury is needed to balance the diminished weight of the overlying air.

Reproduce Torricelli's experiment in a tall building Using a handheld barometer, students will measure the barometric pressure at street level.

Then, emulating the experimenter in the "Connections" video, they will climb the stairs or ascend the elevator of a tall building, measuring barometric pressure at each landing or at several stops along the way.

### Temperature Effects on Density | Sciencing

They observe that the air pressure at the street level is higher than at rooftop level figure 1. For a twelve story building the difference in air pressure is about 4 mb. The building needs to be at least 8 stories high to register an unambiguous barometric pressure difference.

Display should be zoomed so that a month of two at a time is visible. Each pair of students can be responsible for several months of data. Data can be printed out and scotch taped together to form a long time series of a year or more duration.

If printouts from different students are combined, be sure that all students set the plot vertical scale the same.

Temperature and Density

Over time, the barometric pressure at each site goes up and down, up and down. The periodicity is about a week, but the pattern is not very regular. Barometric pressure at the Ridgetop site is always less than at the Open Lowland site. Barometric pressure at Ridgetop and at Open Lowland covary: The difference between the barometric pressure at Ridgetop and Open Lowland is larger than the difference between the high and low pressures at either Ridgetop or Open Lowland.

### Cold air is dense

In other words, the variability in space is greater than the variability in time in this data set. The up and down wiggles of each barometric pressure record reflect weather systems passing across the field area. This could be the subject of a separate investigation, in which students discover the relationship between barometer trends and sunny or rainy weather.

Barometric pressures at the two sites covary because they are subject to the same weather systems. Which site do you think is at higher elevation? Think about the hands-on experiment with the hand-held barometer, and about the experimenter in the connections video. The Ridgetop Site must be at higher elevation than the Open Lowland Site because it always has a lower barometric pressure.

Students should realize that there is a density difference between hot and cold water. Hot water is less dense so it floats on the denser cold water. Ask students to make a prediction: What might happen if you placed the cold blue water on top of the hot yellow water and then removed the card?

Cold water on top Use the same procedure as above, but place the jar of cold water, upside down over the jar of hot water.

Expected results The cold blue water will immediately fall into the hot yellow water causing mixing. The water will quickly become green throughout. Why do you think the hot and cold water mixed when the cold water was placed on top? When the cold water is placed on top, the colors mix because the cold water is more dense and sinks in the hot water.

Give each student an activity sheet. Students will record their observations and answer questions about the activity on the activity sheet. The Explain It with Atoms and Molecules and Take It Further sections of the activity sheet will either be completed as a class, in groups, or individually depending on your instructions.

## Temperature Affects Density

Look at the teacher version of the activity sheet to find the questions and answers. Explore Have students try adding cold and hot water to room-temperature water.

Question to investigate Is there a density difference between hot and cold water? Materials for each group Cold water colored blue in foam cup Hot water colored yellow in foam cup Room-temperature water in clear plastic cup colorless 2 droppers Teacher preparation Add ice to water to make very cold water. Half-fill one foam cup with cold water no ice cubes and another with hot water for each group. Add 2 drops of yellow food coloring to the hot water and 2 drops of blue food coloring to the cold water.