A field guide to the sky. Photographs, plates and plain descriptions for the hundred-odd forms the atmosphere actually makes.https://www.cloudpointapp.com/https://www.cloudpointapp.com/clouds/wall-cloud/https://www.cloudpointapp.com/clouds/wall-cloud/A wall cloud — officially murus — is a localised, often abrupt lowering of cloud from the base of a cumulonimbus, usually beneath a supercell or severe storm. It forms in the rain-free area beneath the storm's strongest updraught, where rain-cooled, very humid inflow air condenses at a lower level than the surrounding cloud base. When a wall cloud shows clear rotation, it can spawn a funnel cloud or tornado.Mon, 03 Aug 2026 00:00:00 GMTLowRarehttps://www.cloudpointapp.com/clouds/stratus/https://www.cloudpointapp.com/clouds/stratus/Stratus is a generally grey, featureless cloud layer with a fairly uniform base, which may give drizzle, snow or snow grains. It forms in stable, moist air lifted or mixed gently, and often appears as hill and coastal cloud. When its base sinks to ground level it is, by definition, simply fog. The sun's outline is usually visible through it, but stratus produces no halos except, perhaps, in extreme cold.Mon, 27 Jul 2026 00:00:00 GMTLowCommonhttps://www.cloudpointapp.com/clouds/fallstreak-hole/https://www.cloudpointapp.com/clouds/fallstreak-hole/A fallstreak hole — officially named cavum — is a clean, often circular gap in a thin sheet of supercooled water-droplet cloud. The droplets are below freezing yet still liquid; when something triggers a few to freeze, ice crystals grow at the expense of the surrounding droplets, which evaporate and open a hole. Wisps of falling ice often trail through the gap. Aircraft punching through the layer are a frequent trigger, leaving circular or linear holes.Mon, 20 Jul 2026 00:00:00 GMTMidUncommonhttps://www.cloudpointapp.com/clouds/horseshoe-vortex/https://www.cloudpointapp.com/clouds/horseshoe-vortex/A horseshoe vortex is a short-lived wisp of cloud curved into a U or horseshoe shape. It forms when a rising thermal carrying a little cloud meets wind that changes with height — wind shear — which tilts and twists the rising air into a spinning, curved ribbon. Because air rises fastest at the warm core of the thermal, the middle bows ahead of the ends, bending the cloud into its horseshoe before it quickly evaporates.Mon, 13 Jul 2026 00:00:00 GMTMidRarehttps://www.cloudpointapp.com/clouds/sun-pillar/https://www.cloudpointapp.com/clouds/sun-pillar/A sun pillar is a vertical column of light that appears above (and sometimes below) the sun when it sits low near the horizon. It is formed by sunlight reflecting off the near-horizontal faces of millions of tiny ice crystals — chiefly flat, horizontally-drifting plate crystals — acting like a field of tilted mirrors. The pillar is not a physical object but the collective glint from crystals along the vertical line between you and the sun.Mon, 06 Jul 2026 00:00:00 GMTHighUncommonhttps://www.cloudpointapp.com/clouds/steam-fog/https://www.cloudpointapp.com/clouds/steam-fog/Steam fog forms when very cold air drifts across much warmer open water. Vapour evaporating from the warm surface meets the cold air, instantly saturates it and condenses into rising wisps and columns that look like smoke. Unlike radiation or advection fog, its moisture comes straight off the water — which is why over the sea it is known as sea smoke.Mon, 29 Jun 2026 00:00:00 GMTLowUncommonhttps://www.cloudpointapp.com/clouds/cumulonimbus/https://www.cloudpointapp.com/clouds/cumulonimbus/Cumulonimbus are the giants of the sky — dense, towering clouds that can stretch from near the ground to the top of the troposphere. They are the only cloud that produces hail, thunder and lightning. As powerful updraughts push the cloud upward, its top flattens into a distinctive anvil when it hits the stable air of the tropopause.Mon, 22 Jun 2026 00:00:00 GMTMulti-levelCommonhttps://www.cloudpointapp.com/clouds/lenticular/https://www.cloudpointapp.com/clouds/lenticular/Smooth, lens- or saucer-shaped clouds that hover, seemingly motionless, near hills and mountains. They form when moist air is forced up and over high ground, creating standing waves downwind. Air condenses into cloud at the crest of each wave and evaporates again as it descends, so the cloud stays fixed in place even as the wind rushes through it.Mon, 15 Jun 2026 00:00:00 GMTMidUncommonhttps://www.cloudpointapp.com/clouds/fogbow/https://www.cloudpointapp.com/clouds/fogbow/A fogbow is a pale, broad arc — like a rainbow drained of its colour — that appears in fog or thin cloud when the sun is low and behind you. It forms by the same refraction and reflection as a rainbow, but the fog droplets are so tiny that the colours smear together into near-white. Pilots see the same effect as a 'cloudbow' encircling their aircraft's shadow.Mon, 08 Jun 2026 00:00:00 GMTLowUncommonhttps://www.cloudpointapp.com/clouds/diamond-dust/https://www.cloudpointapp.com/clouds/diamond-dust/Diamond dust is a ground-level cloud of tiny ice crystals that glitters like floating glitter in the sunshine of very cold, clear days. It forms in frigid polar and high-altitude air when slightly warmer, moister air mixes down and tips the cold near-surface air past ice saturation. Because it is essentially precipitation falling from a clear sky, it can throw halos, sun dogs and light pillars right down at eye level.Mon, 01 Jun 2026 00:00:00 GMTLowUncommonhttps://www.cloudpointapp.com/clouds/virga/https://www.cloudpointapp.com/clouds/virga/Virga is precipitation — rain, drizzle or snow — that falls from a cloud in trailing streaks but evaporates away before it reaches the ground. It shows up as wispy tails hanging beneath a cloud base that clearly fade out partway down. It is most striking over dry regions, where a deep layer of dry air below the cloud dries the falling drops to nothing.Mon, 25 May 2026 00:00:00 GMTMidCommonhttps://www.cloudpointapp.com/clouds/cirrocumulus/https://www.cloudpointapp.com/clouds/cirrocumulus/Cirrocumulus is a high, thin sheet broken into countless tiny white grains or ripples, with no grey shading anywhere. Made almost entirely of ice crystals, it is the least common and most short-lived of the high clouds, often appearing only briefly as cirrus becomes slightly unstable. Its rippled pattern is the classic 'mackerel sky'.Mon, 18 May 2026 00:00:00 GMTHighUncommonhttps://www.cloudpointapp.com/clouds/glory/https://www.cloudpointapp.com/clouds/glory/A glory is a set of shimmering, rainbow-coloured rings centred precisely on the shadow of your own head — most often seen from an aircraft, ringing the plane's shadow on the clouds below, or from a mountain looking down onto fog with the sun behind you. It forms when sunlight is scattered almost straight back toward you by small, uniform cloud droplets. Remarkably, each person sees only their own glory.Mon, 11 May 2026 00:00:00 GMTMidUncommonhttps://www.cloudpointapp.com/clouds/kelvin-helmholtz/https://www.cloudpointapp.com/clouds/kelvin-helmholtz/Kelvin-Helmholtz clouds — officially named fluctus — are a rare and fleeting sight: a neat row of curling crests that look exactly like ocean waves about to break. They form at the boundary between two layers of air sliding past each other at different speeds, where the faster upper layer rolls the cloud tops over into breaking waves. They usually last only a minute or two before smearing away.Mon, 04 May 2026 00:00:00 GMTMidRarehttps://www.cloudpointapp.com/clouds/banner-cloud/https://www.cloudpointapp.com/clouds/banner-cloud/A banner cloud is a plume that streams horizontally from the downwind side of a steep, isolated peak — like a flag flying from the summit — while the surrounding sky stays clear. The classic example flies from the Matterhorn. Strong wind hitting the sharp peak creates a swirling, rising eddy in its lee, where the air cools and condenses into the trailing banner.Mon, 27 Apr 2026 00:00:00 GMTMidRarehttps://www.cloudpointapp.com/clouds/sun-dogs/https://www.cloudpointapp.com/clouds/sun-dogs/Sun dogs, or parhelia, are bright spots that appear on either side of the sun at the same height above the horizon, often tinged with rainbow colour. They form when sunlight is refracted through flat, plate-shaped ice crystals that drift with their faces roughly horizontal, high in cirrus cloud. They sit about 22° from the sun — roughly a hand-span at arm's length — and are most vivid when the sun is low.Mon, 20 Apr 2026 00:00:00 GMTHighCommonhttps://www.cloudpointapp.com/clouds/altostratus/https://www.cloudpointapp.com/clouds/altostratus/Altostratus is a featureless grey or bluish sheet that spreads across much of the sky at mid levels, usually as a warm front approaches. It is thick enough to dim the sun to a pale, watery disc — as if seen through frosted glass — but rarely casts a shadow. When it thickens and lowers into nimbostratus, steady rain or snow is often on the way.Mon, 13 Apr 2026 00:00:00 GMTMidCommonhttps://www.cloudpointapp.com/clouds/crepuscular-rays/https://www.cloudpointapp.com/clouds/crepuscular-rays/Crepuscular rays are the dramatic shafts of sunlight that seem to fan out across the sky when a low sun shines through gaps in cloud or below the horizon. The beams become visible because dust and moisture in the air scatter the light back to your eye, while the shadowed lanes between them stay dark. They are at their best in the hazy air of late afternoon and around sunrise.Mon, 06 Apr 2026 00:00:00 GMTMulti-levelCommonhttps://www.cloudpointapp.com/clouds/shelf-cloud/https://www.cloudpointapp.com/clouds/shelf-cloud/A shelf cloud is a long, low, wedge-shaped cloud that hangs across the leading edge of an advancing thunderstorm, often looking like a vast ramp lowering from the sky. It forms as cold air spilling out of the storm wedges beneath the warm, moist air ahead and shoves it upward to condense. When you see one bearing down, the storm's gusty winds and rain are usually only moments away.Mon, 30 Mar 2026 00:00:00 GMTLowUncommonhttps://www.cloudpointapp.com/clouds/nacreous/https://www.cloudpointapp.com/clouds/nacreous/Nacreous clouds — also called polar stratospheric clouds — shimmer with brilliant mother-of-pearl colours high in the winter sky near the poles. They form astonishingly high in the stratosphere, far above ordinary weather, and need temperatures below about -78°C to condense. Because they sit so high, they keep catching sunlight and glow long after the sun has set on the world below.Mon, 23 Mar 2026 00:00:00 GMTHighRarehttps://www.cloudpointapp.com/clouds/rainbow/https://www.cloudpointapp.com/clouds/rainbow/A rainbow appears when sunlight shines into falling rain from behind you: each raindrop bends the light, bounces it off its back, and splits it into its colours. The light gathers into an arc about 42° from the point directly opposite the sun, with red on the outside and violet on the inside. When a fainter second bow appears outside the first, its colours run the other way.Mon, 16 Mar 2026 00:00:00 GMTLowCommonhttps://www.cloudpointapp.com/clouds/stratocumulus/https://www.cloudpointapp.com/clouds/stratocumulus/Stratocumulus is the low, lumpy grey layer that blankets the sky on so many overcast days — arguably the most common cloud on Earth. It forms when gentle convection near the ground is trapped beneath a lid of warmer air, so the cloud spreads sideways into rolls and patches rather than building upward. Look for rounded clumps with cracks of brighter sky or darker shading between them.Mon, 09 Mar 2026 00:00:00 GMTLowCommonhttps://www.cloudpointapp.com/clouds/asperitas/https://www.cloudpointapp.com/clouds/asperitas/Asperitas is a dramatic, chaotic rippling of a cloud's underside that looks for all the world like the surface of a stormy sea viewed from below. It forms on the base of stratocumulus or altocumulus, where wave motions in the air churn the cloud into rolling, dipping folds. Despite its menacing appearance, it almost always melts away without any storm developing.Mon, 02 Mar 2026 00:00:00 GMTMidRarehttps://www.cloudpointapp.com/clouds/fog/https://www.cloudpointapp.com/clouds/fog/Fog is simply a cloud that forms at ground level, made of tiny water droplets that cut visibility to less than a kilometre. The two most common kinds form in opposite ways: radiation fog settles into valleys on clear, calm nights as the ground radiates away its heat, while advection fog rolls in when warm, moist air drifts over a cold surface such as the sea. One burns off by mid-morning; the other can linger for days.Mon, 23 Feb 2026 00:00:00 GMTLowCommonhttps://www.cloudpointapp.com/clouds/pyrocumulus/https://www.cloudpointapp.com/clouds/pyrocumulus/Pyrocumulus — officially flammagenitus — is a cloud born from intense heat, towering above wildfires and erupting volcanoes. The fierce updraught of hot air lofts moisture and ash high into the sky, where the vapour condenses onto the ash particles to build a dirty, cauliflower-shaped cloud. If the air is unstable enough, it can grow into a full fire-driven thunderstorm complete with its own lightning.Mon, 16 Feb 2026 00:00:00 GMTMulti-levelUncommonhttps://www.cloudpointapp.com/clouds/corona/https://www.cloudpointapp.com/clouds/corona/A corona is a set of soft, pastel-coloured rings that hug tightly around the sun or moon — much smaller and closer to the light than a 22° halo. It appears when light passes through a thin cloud of very small, uniform water droplets, which bend the waves around their edges so they interfere and separate into colour. The most vivid coronae form in thin altocumulus, and are safest to admire around the moon.Mon, 09 Feb 2026 00:00:00 GMTMidCommonhttps://www.cloudpointapp.com/clouds/cirrus/https://www.cloudpointapp.com/clouds/cirrus/Cirrus are thin, wispy streaks high in the sky, often with feathery tails called 'fall streaks' or mares' tails. Because they form so high, they are made entirely of ice crystals. The streaks are crystals falling and being swept sideways by winds that change speed with height. A spread of cirrus moving in often signals an approaching warm front and a change in the weather.Mon, 02 Feb 2026 00:00:00 GMTHighCommonhttps://www.cloudpointapp.com/clouds/morning-glory/https://www.cloudpointapp.com/clouds/morning-glory/The Morning Glory is a rare and spectacular roll cloud — a vast, smooth tube that can stretch from horizon to horizon, appearing to slowly roll about its own axis as it sweeps across the sky. It forms most reliably over the Gulf of Carpentaria in northern Australia, where glider pilots travel to 'surf' the powerful rising air at its leading edge. Rather than an ordinary convective cloud, it marks the crest of an invisible wave rippling through the atmosphere.Mon, 26 Jan 2026 00:00:00 GMTLowRarehttps://www.cloudpointapp.com/clouds/noctilucent/https://www.cloudpointapp.com/clouds/noctilucent/Noctilucent ('night-shining') clouds are wispy, electric-blue clouds seen on summer nights at high latitudes, glowing after the sun has set. They form astonishingly high in the mesosphere — far above all ordinary weather — where tiny ice crystals coat specks of meteor dust. They shine because, although the ground is in darkness, they are still high enough to catch sunlight from below the horizon.Mon, 19 Jan 2026 00:00:00 GMTHighRarehttps://www.cloudpointapp.com/clouds/22-degree-halo/https://www.cloudpointapp.com/clouds/22-degree-halo/A 22° halo is a luminous ring that encircles the sun or moon at a fixed distance — about the span of an outstretched hand held at arm's length. It appears when a thin veil of high cirrostratus fills the sky with millions of tiny hexagonal ice crystals. Each crystal acts as a six-sided prism, bending the light by just over 22°, so the glow piles up into a ring with a curiously darkened sky inside it.Mon, 12 Jan 2026 00:00:00 GMTHighCommonhttps://www.cloudpointapp.com/clouds/mammatus/https://www.cloudpointapp.com/clouds/mammatus/Mammatus are eye-catching, pouch-like lobes that hang from the underside of a cloud — most often the anvil of a cumulonimbus after a storm. Unlike most clouds, which form in rising air, mammatus form where pockets of cloudy, cooler air sink into clearer air below. Their dramatic, sometimes ominous appearance often catches the light beautifully at sunset.Mon, 05 Jan 2026 00:00:00 GMTMulti-levelRarehttps://www.cloudpointapp.com/clouds/cumulus/https://www.cloudpointapp.com/clouds/cumulus/Cumulus are the clouds children draw: bright white, cauliflower tops with flat, slightly darker bases. They form when warm air rises from the ground, cools, and its moisture condenses into droplets. On a sunny day they bubble up through the morning and afternoon, marking columns of rising warm air called thermals.Mon, 29 Dec 2025 00:00:00 GMTLowCommon