https://editor.p5js.org/illus0r/sketches/bgAwlQ1oE

let particles = []

function setup() {
  createCanvas(400, 400)
  noStroke()
  colorMode(HSL, 100)
  for (let i = 0; i < 99; i++) {
    let particle = {
      x: random() * width,
      y: random() * height,
      color: [random() * 100, 50 + random() * 50, 50],
    }

    if (random() < .1) {
      particle.color = [0, 0, floor(random() * 2) * 100]
    }
    particles.push(particle)
  }

  background(220)
}

function draw() {
  for (let particle of particles) {
    fill(particle.color[0],
      particle.color[1],
      particle.color[2])
    circle(particle.x, particle.y, 20)
  }
  noLoop()
}

let particles = []
let center = {}

function setup() {
  createCanvas(400, 400)
  center = {
    x: width / 2,
    y: height / 2
  }
  noStroke()
  colorMode(HSL, 100)
  for (let i = 0; i < 99; i++) {
    let particle = {
      x: random() * width,
      y: random() * height,
      color: [random() * 100, 50 + random() * 50, 50],
    }

    if (random() < .1) {
      particle.color = [0, 0, floor(random() * 2) * 100]
    }
    particles.push(particle)
  }

  background(220)
}

function draw() {
  // translate(width/2, height/2)
  for (let particle of particles) {
    fill(particle.color[0],
      particle.color[1],
      particle.color[2])
    circle(particle.x, particle.y, 20)

    let vecToCenter = new p5.Vector(particle.x - center.x, particle.y - center.y)
    let vecTangent = vecToCenter.copy().rotate(PI / 2).normalize()
    particle.x += vecTangent.x
    particle.y += vecTangent.y
  }
}

let particles = []
let center = {}

function setup() {
  createCanvas(400, 400)
  center = {
    x: width / 2,
    y: height / 2
  }
  noStroke()
  colorMode(HSL, 100)
  for (let i = 0; i < 99; i++) {
    let particle = {
      x: random() * width,
      y: random() * height,
      color: [random() * 100, 50 + random() * 50, 50],
      r: random()*40,
    }

    if (random() < .1) {
      particle.color = [0, 0, floor(random() * 2) * 100]
    }
    particles.push(particle)
  }

  background(220)
}

function draw() {
  // translate(width/2, height/2)
  for (let particle of particles) {
    // if (particle.r < 0) continue
    particle.r = 5*(noise(particle.x/100, particle.y/100,frameCount/100)-.2)

    fill(particle.color[0],
      particle.color[1],
      particle.color[2])
    circle(particle.x, particle.y, particle.r)

    let vecToCenter = new p5.Vector(particle.x - center.x, particle.y - center.y)
    let vecTangent = vecToCenter.copy().rotate(PI / 2).normalize()
    particle.x += vecTangent.x
    particle.y += vecTangent.y
  }
}

https://github.com/processing/p5.js/wiki/Global-and-instance-mode

let particles = []
let center = {}

function setup() {
  createCanvas(400, 400)
  center = {
    x: width / 2,
    y: height / 2
  }
  noStroke()
  colorMode(HSL, 100)
  for (let i = 0; i < 256; i++) {
    let particle = {
      y: (i % 16) * width / 16,
      x: floor(i / 16) * height / 16,
      color: [random() * 100, 50 + random() * 50, 50],
      r: random()*40+100,
      rk: .89+.1*random(),
    }

    if (random() < .1) {
      particle.color = [0, 0, floor(random() * 2) * 100]
    }
    particles.push(particle)
  }

  background(220)
}

function draw() {
  // translate(width/2, height/2)
  for (let particle of particles) {
    if (particle.r < 0.1) continue
    // particle.r -= .1*(noise(particle.x/100, particle.y/100,frameCount/100)-.2)
    particle.r *= particle.rk

    fill(particle.color[0],
      particle.color[1],
      particle.color[2])
    circle(particle.x, particle.y, particle.r)

    let vecToCenter = new p5.Vector(particle.x - center.x, particle.y - center.y)
    let vecTangent = vecToCenter.copy().rotate(PI / 2).normalize()
    let speedTangent = vecTangent.copy().mult(.4)
    let speedNoise = new p5.Vector(
      noise(particle.x/100, particle.y/100,frameCount/10) - .5,
      noise(particle.x/100, particle.y/100,frameCount/10+999.) - .5
      ).mult(3)
                                   
    particle.x += speedTangent.x + speedNoise.x
    particle.y += speedTangent.y + speedNoise.y
  }
}