Abstract: A sensor assembly includes a housing and a sensor unit attached to the housing. The sensor unit includes a cylindrical shell defining a vertical axis and rotatable around the axis relative to the housing. The cylindrical shell extends upward along the axis from a lower edge. The sensor unit includes a first frustoconical panel fixed to the cylindrical shell, centered on the axis, and extending downward and radially outward from the lower edge. The housing includes a second frustoconical panel centered on the axis, defining a gap with the first frustoconical panel, and defining an airflow outlet from the housing radially inside the second frustoconical panel relative to the axis. The sensor unit defines an airflow inlet radially inside the lower edge relative to the axis and positioned to receive airflow from the airflow outlet. At least one of the frustoconical panels includes a ridge extending into the gap.

Abstract: A sensor apparatus includes a cylindrical sensor window defining an axis oriented substantially vertically, an air nozzle positioned below the sensor window and aimed upward, and a sensor-housing-top cap positioned above the sensor window and including a sensor-housing top and a circumferential cap. The sensor-housing-top cap is a single piece. The circumferential cap includes a topside and an underside. The topside and the underside are disposed radially outward from the sensor window. The underside includes a groove having a cross-section elongated circumferentially around the axis. The cross-section of the groove curves from a lower end upwardly and outwardly to an upper end.

Abstract: A sensor apparatus includes a cylindrical sensor window defining an axis oriented substantially vertically, an air nozzle positioned below the sensor window and aimed upward, and a sensor-housing-top cap positioned above the sensor window and including a sensor-housing top and a circumferential cap. The sensor-housing-top cap is a single piece. The circumferential cap includes a topside and an underside. The topside and the underside are disposed radially outward from the sensor window. The underside includes a groove having a cross-section elongated circumferentially around the axis. The cross-section of the groove curves from a lower end upwardly and outwardly to an upper end.