Rough estimates of the upper r_upper (dashed red line) and lower r_low (solid blue line) turning points of the thermal mode R₂ shown in Figure 2. We use the frequencies and wavenumbers of the modes as measured along the ridge as inputs to the scaling relations r_low/R_⊙ ≈ 1–3Ω_⊙/(sσ) and r_upper/R_⊙ ≈ 1–5σ/(16sΩ_⊙) (B. W. Hindman & R. Jain 2022). Although these theoretical relations describe a cavity that straddles the entire solar convection zone, thermal modes are not observed in the shallow surface layers r/R_⊙ ≳ 0.98. Thus, we cannot comment on the depth penetration of these waves and the thermal-mode cavity size unless we directly observe them propagating at those layers. If the modes were to indeed propagate as deeply as suggested in this figure, it would suggest that the bulk is effectively nonconvecting.