Simulators / APES Unit 7 / Topic 7.3

Thermal Inversion Simulator

Find the warm air lid in a temperature sounding, then run a valley city through a full day. Watch the same cars and factories build up clean air or dangerous air, depending on where the lid sits. Free, with no login.

Sounding

A sounding is a set of temperature readings at different heights, like a balloon carrying a thermometer up.

Choose a sounding

Release a puff of smoke

The puff starts 5 °C warmer than the ground air and cools 2 °C for every 200 m it climbs. It keeps rising only while it is warmer than the air around it. Where it stops is the lid.

Try these

Climb the puff through S1, then S3. Which has the lower lid, and by how many meters?
Compare the lid to the height where the air line first bends toward warmer. What do you notice?
Pick Custom. Slide the warming to 0 and then to 3. How low can you push the lid?

Lid table

A row fills in each time you finish a sounding.

Sounding	Lid height	Open layers	Warm layer above?

Ground-level count through the day

Valley log

E = puffs added by traffic and industry. W = puffs removed by wind and cleanup. Ground = total puffs divided by open layers, rounded up.

Time	Sounding	Lid	Layers	E	W	Total	Ground	Quality

Illustrative data: all temperatures, emissions and counts are hypothetical. The Air Quality Score here is made up for teaching. It is not the real Air Quality Index.

Take it to class

Lid on the Valley

The simulator shows the pattern. Lid on the Valley is the classroom activity that goes with it: students walk a smoke parcel up five temperature soundings, build a valley board with a sliding lid, run a normal day and a stuck-high day, and defend a policy recommendation with a claim, evidence and reasoning.

Hands-on model

A printable Valley Board, a cut-out lid strip and about 40 paper puffs. The digital version runs in any browser.

Data and decisions

Five soundings, three runs, five policy cards and a graph that ties the lid height to the ground-level count.

Teacher guide and key

Pacing for 60 to 75 minutes, common mistakes, debrief questions and a full answer key.

Get Lid on the Valley free on TpT

About the model: each round is 3 hours. A sounding gives the lid height, and the lid height divided by 200 m is the number of open layers. Puffs added by traffic and industry and puffs removed by wind and cleanup change the total. Puffs spread evenly through the open layers, and any leftover stays low, near the tailpipes. The ground-level count is the total divided by the open layers, rounded up. Nothing escapes through the lid. That is the one big simplification, and it is the whole point of the lesson. Real inversions leak a little, and the parcel method and the 10 °C per km dry cooling rate are supporting detail beyond the CED.