title: Unable to change default radius value using folium CircleMarker
body: <p>I am unable to change the default circle marker size in folium.</p>
  
  <p>This is what my code looks like:</p>
  
  <pre><code>import folium
  import pandas as pd
  
  data = pd.read_csv("Volcanoes_USA.txt")
  map = folium.Map(location=[46,-120],zoom_start=5)
  fg = folium.FeatureGroup(name="My Map")
  
  def colorcode(x):
      if x in range(0,1600):
          color = 'green'
      elif x in range(1600,2200):
          color = 'orange'
      elif x in range(2200,2800):
          color = 'red'
      else:
          color = 'darkred'
      return color
  
  lat = list(data["LAT"])
  long = list(data["LON"])
  elev = list(data["ELEV"])
  
  for lt,ln,el in zip(lat,long,elev):
      fg.add_child(folium.CircleMarker(location = [lt,ln],
                                 radius = 10,
                                 color = 'black',
                                 fill_color = colorcode(int(el)),
                                 fill_opacity = 0.6,
                                 popup = "Elevation: %s meters" %el))
  
  map.add_child(fg)
  map.save("Volcanoes1.html")
  </code></pre>
  
  <p>And this is how my output looks no matter whatever radius value I use.
  <a href="https://i.stack.imgur.com/kz0HR.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/kz0HR.png" alt="enter image description here"></a></p>
  
  <p>Can someone please help?</p>
  
  <p>Regards</p>