MS-ESS2-5: How Air Masses Change the Weather
Also called NGSS MS-ESS2-5 · Topic: Weather and Climate · Earth and Space Science
The Official Wording
Collect data to provide evidence for how the motions and complex interactions of air masses result in changes in weather conditions.
Clarification statement: Emphasis is on how air masses flow from regions of high pressure to low pressure, causing weather (defined by temperature, pressure, humidity, precipitation, and wind) at a fixed location to change over time, and how sudden changes in weather can result when different air masses collide. Emphasis is on how weather can be predicted within probabilistic ranges. Examples of data can be provided to students (such as weather maps, diagrams, and visualizations) or obtained through laboratory experiments (such as with condensation).
Assessment boundary: Assessment does not include recalling the names of cloud types or weather symbols used on weather maps or the reported diagrams from weather stations.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What MS-ESS2-5 Means in Plain English
Students gather temperature, air pressure, humidity, wind and rain data and use it to show how moving air masses change the weather in one place. They notice that air flows from high pressure toward low pressure, and that a clash of warm and cold air brings sudden change.
Memorizing cloud names or map symbols is not the goal, and forecasts are given as chances, not certainties. This builds on the water cycle model (MS-ESS2-4) and leads to how global circulation shapes climate (MS-ESS2-6).
MS-ESS2-5 I Can Statements
- I can record weather data and spot when it changes suddenly.
- I can explain how air moves from high to low pressure.
- I can use data to show what happens when a cold front passes.
MS-ESS2-5 Worked Example
A two-week weather log from the school's own instruments that catches a cold front passing through.
What happens to our local weather when a new air mass moves in?
Set It Up: A classroom barometer, thermometer, hygrometer and wind vane, read at the same time each afternoon for two school weeks.
- Record pressure, temperature, humidity and wind direction every afternoon at 1 p.m.One row per day in the log
- Plot pressure and temperature on the same timeline.Two lines across 10 school days
- Find the day the pressure falls the most.Day 6: 1018 hPa down to 1006 hPa
- Compare the readings just before and just after that drop.Before: 24 °C, 75% humidity, south wind. After: 13 °C, 40% humidity, northwest wind
- Note what the weather did on the day the readings flipped.Gusty wind and a short, heavy shower
- Follow the pressure for the next three days.Climbs to 1022 hPa, clear skies
A cold, dry air mass replaced warm, humid air on day 6, bringing a pressure dip, a quick storm, an 11 °C temperature drop and a wind shift.
Why it works: Air moves from high toward low pressure, and when denser cold air pushes under warm, moist air, the warm air rises and cools until its water vapor condenses into storm clouds.
Common Mistakes with MS-ESS2-5
Using one reading as proof
“It was cold today, so a cold front came through.”
Try this: Look for several changes together over a day or two: falling then rising pressure, a temperature drop, drier air and a wind shift.
Wind blowing toward high pressure
An arrow drawn from the L toward the H on a weather map
Try this: Air is pushed from crowded, high-pressure areas toward low pressure, so wind arrows point away from the H and toward the L.
Expecting forecasts to be certain
“It said 70% chance of rain and stayed dry, so the forecast was wrong.”
Try this: A 70% chance means rain on about 7 of every 10 days like this one, so some dry days are expected.
Where MS-ESS2-5 Fits
Practice MS-ESS2-5
Quick Check
- The barometer reading falls quickly all morning. What kind of weather might be coming?
- After a cold front passes, what usually happens to temperature and humidity?
- Why does wind blow?