用ajax调用更新了css转换

I would like to ask for help regarding a CSS transition which works but is not working when I update the page with an ajax recall.

I try to explain:

I defined a compass CSS object and an arrow of this compass which should be oriented in the compass as the wind does (wind direction is updated every second).

I created a CSS object and the arrow moves to the initial position slowly with the transition effect. Then every second there is an update of the wind data and I use an Ajax call to update the page.

Consider that the windDirUpdater function is returning the updated wind direction (json['now']). The arrow updates the position but without transition. Can anybody help me, please?

Below is the part of the code which I am using now to define the CSS object and the ajax recall. Thanks Fabio ruzzi.f@gmail.com

</style>

<table style="width:98%;margin:0 auto">

        <tr>

            <td>

                <div class="compass" id="nowDirDiv">

                    <div class="direction">

                        <p style="font-size:1.2em"><?php echo $direction['nowwind']?> <?php echo unitFormatter($displayWindUnits)?><span><?php echo $direction['nowdir']?>° (<?php echo $direction['nowdirabb']?>) </span></p>

                    </div>

                    <div class="arrow x<?php echo $direction['nowdir']?>"></div>

                </div>                  



            </td>
        </tr>



        <script> 
            windDirupdater();

            setInterval(function(){ windDirupdater(); }, (1*1000));


            function windDirupdater(){

                $.ajax({

                    url : "homepage/blocks/windDir/windDirUpdater.php",

                    dataType : 'json',

                    success : function (json) {

                            html = '<div class="direction"><p style="font-size:1.2em">'+json['nowwind']+' <?php echo unitFormatter($displayWindUnits)?><span>'+json['nowdir']+'° ('+json['nowdirabb']+')'+'</span></p></div><div class="arrow x'+json['nowdir']+'"></div>';
                            $("#nowDirDiv").html(html);


                    }

                })

            }



    </script>