Fa2004 16.33312-9 Wind shear Wind shear is of special interest because it involves significant loca changes in the vertical and horizontal velocity (e nowara ft Particularly important near airports during landings Simple analysis -consider the case shown, where the change in(hor izontal) wind velocity is represented by du a)△h where Ah corresponds to changes in altitude(what we previously just Value du/dh gives magnitude of wind shear, which is 0.08-0.155- for moderate and 0. 15-0.2s for strong Mean wind Flight path Glide slope Flare Figure 3: Aircraft descending into a horizontal windshear But can write the changes in altitude( use h= Ah/At)as h=U0(6-a)� � Fall 2004 16.333 12–9 Wind Shear • Wind shear is of special interest because it involves significant local changes in the vertical and horizontal velocity (e.g. downdraft) – Particularly important near airports during landings. • Simple analysis – consider the case shown, where the change in (hor￾izontal) wind velocity is represented by du ug = Δh dh where – Δh corresponds to changes in altitude (what we previously just called h) – Value du/dh gives magnitude of wind shear, which is 0.08–0.15s−1 for moderate and 0.15–0.2s−1 for strong. Glide slope Flight path Flare Mean wind Figure 3: Aircraft descending into a horizontal windshear • But can write the changes in altitude (use h˙ = Δh/Δt) as h˙ = U0(θ − α)